0:33 Intro. [Recording date: March 25, 2019.] Russ Roberts: My guest is author and economist Emily Oster.... This is her third appearance on EconTalk. She was here last in 2014 talking about infant mortality; and before that we talked about her book Expecting Better. Today we are talking about her new book, Cribsheet: A Data-Driven Guide to Better, More Relaxed Parenting, from Birth to Preschool.... Your book has a phenomenal title--'cribsheet' is genius. But the content is also superb. It is such a sensible book, and as helpful as it will be to mothers dealing with issues such as breastfeeding, post-partum depression, it might be even better for new fathers to read, because they will often struggle--at least in my experience--to understand the physical and emotional challenges of childbirth and its aftermath. And you deal with those in a totally straightforward and illuminating manner. I want to start with the issue of breast feeding versus formula. It came up recently in an episode with Amy Tuteur. Your book is data-driven. What do we know about this as a choice? What do we know about the--what are the studies? And, what is the evidence such that it is on this question that's very important to every new family? Emily Oster: So, the thing that--I should just start with saying what's hard about breastfeeding, which is that many of the outcomes we want to look at--things like, 'Is breastfeeding important for kids' health?' or 'Is breastfeeding important for how kids do in school?'--all of those outcomes are also linked with all kinds of things about families. So, you know, for example, moms with more education tend to have kids who do better in school. That's just something we know from other data. It is also the case that moms who breastfeed tend to be different from those who don't, and in particular they tend to more educated, they tend to be richer, they tend to have more stable family structures-- Russ Roberts: In the United States. Emily Oster: In the United States. Absolutely. And that's actually--there's sort of some interesting dynamics that's actually become much more true over time since the 1970s, when there was sort of a resurgence of breastfeeding in general. And the resurgence was much larger among sort of some kinds of women than others. But, you know, whatever the reason, when you then go to try to look at the relationship between breastfeeding and outcomes, if you just do what we think of as sort of the simplest thing, like compare the kids of women who breastfeed to the kids of women who do not, maybe some of what you are picking up is the impact of breastfeeding; but so much of what's driving differences between those kids are other things about their families. And so, when we sort of step back and try to say, 'Okay, let's really understand which of these links are true,' it's really very hard to use these kind of basic, what we call 'observational studies,' where they just compare kids who are breastfed to kids who are not--because there as so many biases in those studies. And so, when I look at this, I really try to drill into studies that are what I would say, better, or making more convincing causal claim. And there's kind of two kinds of studies that I think are more compelling. So, one, are studies--are Randomized Control Trials. And unfortunately, there is one of those-- Russ Roberts: A small number-- Emily Oster: It's a small number. It's a big study-- Russ Roberts: --bigger than zero. Emily Oster: It's bigger than zero. And the study itself is big. And it was run in the 1990s, in Belarus. I mean, there are some things about this study that are not ideal. But, it did do sort of some of what we would like, which is: encourage some women to breastfeed and some women didn't get that encouragement. And indeed there were differences in breastfeeding rates in the two groups. And you can then, you know, compare their kids and try to draw causal conclusions. The other kinds of studies that I like a lot are sibling studies, where they compare two siblings--two kids born to the same mom--where one kid was breastfed and one kid was not. And that is going to address at least some of the kinds of biases that we worry about--because the moms are the same. It's the same mom. So, things like, 'Oh, I'm worried the moms are different,'--that will obviously not be a concern in a sibling study. When you focus on those kind of studies, you find much, much, much more muted benefits than the sort of grandiose claims that are made in a lot of the public discussion of breastfeeding. So, it is true: It looks like there are some early-life benefits, particularly around digestion. So, it looks like kids who are breastfed are a bit less likely to get sort of gastrointestinal diseases in the first few months, in the first year, and maybe a bit less likely to have, you know, rashes in the first year. So these effects are significant. They are not enormous. Russ Roberts: Meaning statistically significant. Emily Oster: Yeah. They are statistically significant. But they are not especially large. And these are pretty minor--for the most part pretty minor complications. What these studies don't find support for are things like impacts of breastfeeding on IQ [Intelligence Quotient]. Impacts of breastfeeding on obesity. Impacts of, you know, among the kids later. Impacts of breastfeeding on eczema or allergies in the long run. So, many of the claims that are made just do not have support when we look at the best data. And so, I think, what I try to do in the book is sort of drill into those and help people understand: Why might you have thought that there were these other links, and why is that evidence not as good as the sibling evidence or the randomized evidence? And, you know, what can we really learn about these--what can we really know about these impacts? Russ Roberts: You write about it really extremely well. I was going to say, 'for an economist.' Which is damning you as faint praise. But you write about it extremely well, period. Meaning: You make it understandable to a non-economist why interpreting these data or these studies are a little bit challenging. I want to make one point about the sibling study that you raised. And that was, I would just mention in passing, the study that Amy Tuteur leaned on in her defense of not breastfeeding: because the sibling study finds very small effects. You point out, correctly, though, in your book that one has to ask why one sibling might be breastfed and not another. It is true that the mother is held constant in those situations. But, what's not held constant--it's not random. They don't tell a mom, 'Oh, why don't you breastfeed one of the kids and not the other and then we'll do a study later?' We don't know the reason. And that could have an effect. So, it's just worth mentioning. Emily Oster: Yeah. I agree. And I think we always want to be interrogating all the kinds of studies that we have. And there, I think it's often worth thinking about: What are the likely--what are the likely biases? Like, what are some of the reasons why you might breastfeed one kid and not the other? I think that some of those are situational. Maybe some of those are about the kids. So, I think it is worth giving some thought to that. One of the sort-of kinds of studies that I like here are ones where they sort use the siblings and they do the kind of biased--what we'd say like the biased regression with the same kids. So, they compare the siblings without holding the mom constant; and then they compare the siblings while holding the mom constant. And that is kind of a nice way to illustrate sort of what happens as you include this control: What happens to the bias? I think those are good for illustrating some of these problems. Russ Roberts: The power of mom. Very large. Emily Oster: Exactly. Very big.

8:26 Russ Roberts: Would you reflect--you talk about this a little in the book, but I'd like you to reflect on, to hear it as well--the cultural bias, if any, in favor or against breastfeeding? And the challenges of breastfeeding? I think for those of us who are men--or women who have not had children--we just assume it's "easy." There's hardly anything you could imagine that's more natural. And yet it's not so straightforward. So, talk about that a little bit. Emily Oster: Yeah. I think that one of the things that makes this conversation so fraught and uncomfortable in some ways is that people, again, sort of assume it's very easy. So, it's like, 'Even if there's just some small benefit, why wouldn't you do it? It's so easy.' And if, on the other hand, it is not that easy for a lot of women. So, I think, many, many women--I certainly did, I think--I certainly did, I think--almost everybody struggles with breastfeeding. At the beginning it's actually hard to kind of figure out how to do it. Your baby has never done it before, because they've just been born. And so, they are kind of figuring it out. Particularly if you are a first time mom, you are figuring it out. And you are--people are often quite delicate with their baby, but it turns out you kind of have to like jam it on there. And, it's just like--it's hard. And then people's milk doesn't come in. And I think this adds--there's this sort of societal pressure around breastfeeding. People say, 'But don't you want to give your kid the best start? This is the best start.' It's [?] 'the best start.' And I think that that kind of wraps up with this difficulty. It's like, 'Here's this thing. It's the best start. It's the first thing I can do for my baby. And I'm failing them. I'm just a huge failure.' And I think that--that is such a hard thing. There's such a lot of pressure to put on moms in these very first moments of life. And so I think some of what I want to do with this discussion of breastfeeding in the book is to just take a little bit of that off, and say, 'Hey, you know, yeah. This could be great and a lot of people really like to do it,' and, you know, by the way, there's a whole other chapter in the book about how you can make it work, and, you know, what are some tips for making it work better. But, you know, if it doesn't work, and it doesn't work for you, it isn't the thing that's going to make your kid the successful, a successful, adult. I mean, there's no thing like that. But this isn't, even if there was one. And so, just to sort of take a little bit of that off and tell people, 'You know, it's okay. You are not failing. You are not a bad mom, three minutes in, if it doesn't--if your baby doesn't immediately crawl up your belly and start nursing. That's not the thing that's going to make you a good parent or good mom. Russ Roberts: Yeah. Well, fortunately women aren't very emotional at that time-- Emily Oster: No. It's a very calm-- Russ Roberts: Easy come, easy go-- Emily Oster: A very calm time.

11:19 Russ Roberts: I mention that, as I made that remark I realized how politically incorrect that statement sounded. But I do want to mention that post-partum depression, which you talk about in the book in some detail and share some very powerful personal stories of your own--it's something that--it's just a phrase, 'post-partum depression'. And, for new fathers, they are just clueless. And, I'm sure, most women, of course, are unprepared for it as well. But, when you see that your wife is not the person that you know--which they struggle to be in the first days, sometimes longer after childbirth--bursting into tears uncontrollably over things that you can't understand--it's really important for men to understand. It's good for women, too. But men have zero idea what's going on, I suspect, in many situations like that. And it's good to be aware of that. And your book does a really good job. Emily Oster: Yeah. And I think it's important also to sort of distinguish between, sort of postpartum depression and the sort of hormonal insanity, almost of that the woman's insane--it's the hormones--of the sort of first few days. I think almost all women in the first few days after birth are very emotional. And things--you just kind of cry for no reason. And that's like super-common. And not, that it's not something to be worried about, but it's sort of not something to, like, over-react to. But, as, you know, if that sort of continues and people don't have interest in the baby, in particular, that's, then we're sort of moving into post-partum depression. But I think that it can be very hard. Many women say, sort of experience more significant post-partum depression, say, you know, 'It's so hard to see from the inside.' Because when you are struggling with depression, post-partum or otherwise, it's sort of--things--you are not seeing it from the outside and saying, 'Oh, it's just because of depression that I feel this way.' So, I think, in part, that is why, if anything, if I was going to tell, you know, people--the non-birth parent, spouse--to read anything in the book it would be that chapter. Because I think being able to see some of those things and recognize them could be really valuable for a lot of families. Russ Roberts: Yeah; and the--I guess the more--the gentler phrase is 'baby blues'--short of depression, but as you point out, it's just an emotional time. And there's often a lot of crying. It's totally normal. But if you are not prepared for it, it's hard. Emily Oster: Yeah. It's overwhelming. Russ Roberts: Yeah, it's very hard.

14:04 Russ Roberts: One of the things that I love about the book--because I'm an economist--is that you focus on tradeoffs. In many of the situations you talk about the, the evidence is either weak or suggestive. It's often not definitive. And there's going to be tradeoffs and things to deal with and choices. So, in this case between breastfeeding and formula, I think a lot of people would say, 'Well, there's no harm in breastfeeding. And it has some small benefit, at least. It may be larger.' But you point out there's costs to breastfeeding. Just like there are costs to formula. But they are very different natures. And each person has to make their own choice. And your general philosophy in the book is to respect the choices people make. Emily Oster: Yeah. And I think in some ways that's very different than my first book, than Expecting Better, where a lot of what I was writing about were things like, 'Is it okay to have sushi?' 'Yes.' And, there's sort of, like, the process of the book was like, telling people, 'Look, here, this is okay to do and here is why.' You know, in at least some of the situations. And I think there's many more things in parenting where, you know, of which breastfeeding is one, where it's like, 'Yeah, so there's some small benefits or maybe there's some small costs.' But so much more important than that is thinking, structuring the decision in a way that takes seriously these costs and benefits, but also thinks about the preferences of the parents: What works for your family? And I think that is sometimes missed in these discussions of babies that there is so much emphasis put on investing in the kid, and thinking about what is right for the kid at infinite cost, sometimes it seems like, to the family. And sort of, I would encourage, I mean, part of my [?] is that people are being encouraged to think about some of these choices and how they think about the family more broadly, not just the baby. Russ Roberts: Yeah. The challenge, of course, is that if you are miserable, you are not going to be the best parent you can be. And so there is some tradeoff between misery and being a good parent. Emily Oster: Yeah. And I hear--I hear often from, so, you know, people send me email sometimes. And, the ones that I get that I just wish I could sort of reach through the computer are when people are like, 'I'm writing this because my wife,' like, 'we have a 4-week old, and my wife is like trying to breastfeed all the time, and it's going really badly, and I feel so terrible for her. And I don't know how I can help. And if only I could tell her like this wasn't the most important thing that she could ever do, and it was going to be okay if she didn't do it, like I think that would really help.' And those are the times that I'm like, 'Okay. You know, we have to help people, sort of see the reality here.'

16:52 Russ Roberts: Let's talk about co-sleeping. What is it and what do we know about it? Emily Oster: So, co-sleeping refers to the practice of having your baby sleep in the bed with you. And, this is another very controversial parenting practice, where I think you get very high emotions on both sides. So, sort of, on the one side, sleeping in bed with your baby is not recommended by the American Academy of Pediatrics [AAP]. They are concerned about a higher risk of Sudden Infant Death Syndrome--SIDS. Or suffocation under a sleeping parent. So, their sort of party-line, from the AAP, is that you should not co-sleep with your kid. The--on the sort of flip side--the, a group that, it's broader, but let's say the, like attachment-parenting space, is, says, 'This is the natural way to sleep with your kid.' And, 'This is the way people have done it for millennia.' And, you know, 'It's totally fine. And the AAP is, you know, overstating the risks and they don't really know anything about data.' And, you sort of see both sides, kind of really dig in. Dig in here. And I think part of it is that this an experience that people really care about. It's a lot of the time with your kid. And so I think, you know, the truth lies, sort of somewhere--like, breastfeeding lies somewhere in the middle of those two extremes. So, co-sleeping can be very risky. And, in particular, if you are--the parents are smoking or drinking, it is very dangerous to co-sleep. Smoking increases risk of SIDS for other reasons. Parents who are drinking heavily are sleeping more heavily and less likely to notice if they're lying on a baby, unfortunately. So, if we look at data on this, the evidence suggests that that combination--that sort of drinking and smoking and co-sleeping together is a very dangerous combination. But, when you look at parents who do the co-sleeping in what we'd say is sort of the safest way--so, with parents who are not smoking, who are not drinking, who are not in bed without any extra pillows and so on--you know, there are some risks. There are some increases in death rates. But they are very small. And I think part of what makes this very hard to think about is, you know, this is of course the worst outcome you could imagine as a parent. On the other hand, this is the choice we have to make; and by not acknowledging the choice by saying, sort of, 'Okay, well actually I'm not even going to think about this as a possibility,' I think we are not forcing ourselves to think about the decision correctly. And so, you know, if you choose to go to sleep, you do it as safely as possible. The risk is there, but it's very small. And it's small in comparison to risks that people are taking every day, like putting their kid in the car. So, I can see why people would choose to do this. I can see why people would choose not to. And I think in sort of both cases, we really want to be making those choices with a fully understanding of what the actual risks are; and also how to mitigate them. Russ Roberts: And, as you point out, sleep training, which is a big challenge for new parents--actually any kind of parent, because shifts[?] aren't the same--it's not always, unfortunately you can't always take the lessons from the first kid and apply them to the second kid. It's kind of like a little bit of a Ground Hog day thing going on there. One of the challenges of a newborn is they cry a lot. Some sleep through the night; most of them don't. You get cranky trying to deal with it; you don't sleep so well. You're not the best parent, as a result. And, co-sleeping tends, in some people's experience, leads to better parents and better kids. At least for a while. And that kind of trade-off, again, against the very small risk that you talked about, is a normal thing to think about. Nothing is right or wrong there. Emily Oster: Yeah. And I think it's just--in these conversations somehow we get into these discussions where it seems like people just want you, just want to convince other people that the choices they are making are the right ones for everyone. So, if you choose to co-sleep, there is somehow then the instinct to be like, 'Well, everyone should co-sleep. Because it's the right choice. Because I would only make the right choice.' And I think, one of the things I say a lot in the book, is, 'Something can be the right choice for you and not the right choice for other people.' And so, we can all see the same data and make different choices, and they can all be the correct choice. And so I think sometimes we really need to step back. And, I mean, I'm like the bossiest person on the planet Earth, and so I always think that I should be bossing people to tell them the things that they should do with their kids. But, actually, when I wrote this book, I tried to [?], like, 'Okay, actually, this is different; this is maybe not the place we should be as the bossiest.'

22:11 Russ Roberts: We had Sebastian Junger on the program. And, in his book, Tribe, he talks about--he talks very powerfully about the virtues of co-sleeping. He says: Throughout human history, through ancient times, we never put kids in their own room. We were all in the same cave, or the same hut or wherever we were in. And it seems somehow cruel to put kids in their own room--to exile them to a different tent. And he actually makes the suggestion--I don't know if it's his or from somewhere else--that the reason kids become so attached to their teddy bear or their blankie or whatever it is in their bed is that they are desperately lonely. And they turn to whatever they can for comfort--this is in the bed. And, it's not a parent. And, I found that poetic and interesting. I don't know if it's true. And I think you would concede we don't know whether it's true, either. It's a tough thing to test. Emily Oster: I agree. Yeah. We don't, like, I guess that could be true. I am not sure what we would do. I think, I have sort of two reactions. One is, I'm not sure what we would do with that, because, you know, I don't know, like: What are the outcomes, the sort of long term outcomes that we are thinking about there that we would be interested in evaluating? So, if the thing we're concerned about is loving the teddy bear, that's obviously, itself, not a big deal. I understand that there's some deeper thing about not being able to form attachments to other people, maybe. But, I'd want to be a little more specific about, kind of, what are the downsides we're seeing. And the other piece, there--and you see this, you see this a lot in this co-sleeping discussion and attachment parenting more broadly about the idea that, you know, this is how it was always done. I mean, there are a lot of things that are different about modern society than when people were living in one cave together. And so, I'm like, on the one hand I kind of see the point; on the other hand I am not sure where to take that argument. And the kind of skills that people need are different from living in caves. So, I find that interesting, I guess, but I'm not sure it's so relevant to the kind of parenting people are doing these days. Which isn't to say that, again, that you shouldn't co-sleep with your kid if that is something that you like. I mean, for some people, this is like a great experience. They love having their kids in their bed; and they like to have their kids in their bed until they are old; and it's--if you don't get to see your kids during the day, it's like nice to see them at night. I think the thing, that--some people don't like that, though. I think we have to acknowledge, like, some people do not want their children in their bed. Russ Roberts: Well, going back to the Sebastian Junger point, it's possible through human history drunk, exhausted parents after a day of foraging and hunting, rolled over on their kids and killed them a lot. So, it's not a--it's not--there's a lot of romance to that story. It happens to appeal to me. We were not religious about co-sleeping--most of our kids slept in their own beds. They were allowed to come in, in the morning; and they may have stayed at night for a while. But I do understand the appeal of that. Amy Tuteur calls it a 'paleo-fantasy.' I don't know if, that kind of thing, she calls that, I don't know if that's--there's no way of knowing. I think just an important aspect of life that I'm increasingly interested in, and your book makes me think about, that, a lot of the things we want data on, we don't have. And we are just going to have to deal with that. It's just the way it is. Emily Oster: Yes. You have to make these choices with limited information. You're going to have to choose whether to have your kid in your bed or not in your bed. There's only two things. You can only have them in one of the two places. And you are not going to have unlimited amounts of perfect data to evaluate the full consequences of that. But you still need to make the choice. And that's true of so many things in parenting. And also in all other parts of your life. Russ Roberts: I don't know if you remember it off the top of your head, but there's a beautiful story you tell in the book about your daughter's reaction to your son's struggling to fall asleep. When you and your husband are dealing with this challenge with your second child. And, you'd already gone through it with the first child. Of course, sometimes that brings back tough memories. And it's very, very hard for many parents--most, almost all parents--to hear their kids cry. You know, you come back from the hospital and it's like, 'What do we do? How do we get into this?' It's hard to get out of the car when you come back from the hospital. It's like, no manual; parents aren't here; and they are crying. And it breaks your heart. It's designed to break your heart. It's very effective. Or made to--'designed' is not necessarily the right word. But it breaks your heart. Do you remember what your daughter said when-- Emily Oster: Yeah. Yeah. So this is when we were sleep-training then and as you say, you know, when you are sleep-training your kids, it is very hard to hear them cry. But, you know, it was the right choice for us. And we'd done it with Penelope and at this point she was, you know, 4 and a half or something, so I was, you know, kind of upset, and we could hear him crying from her room, we were urging bedtime, and she says, 'Mom'--as I'm kind of upset, and I said, 'You know your Mom is kind of upset because of the crying.' And Penelope said, 'Mom, we have to help Finn[?] learn to sleep.' Like, it's important that you do this. And she was very serious about it. I mean, she continues to have a lot of opinions about child-rearing with her brother. Russ Roberts: Heh, heh. No doubt. Emily Oster: But it was of course in that moment, you're like, 'Okay. I guess maybe it's going to be okay.' Because it was okay with the first kid. And I think in some sense that's really like the realm of anecdote. Russ Roberts: Sure. Emily Oster: But, for me, like that, even though I had made the choice to do sleep-training based on data and evidence, still, in that moment, it was very nice to sort of get the anecdote, reinforcement. Russ Roberts: And it's imaginable that if it had gone particularly badly, you might have decided to change course in the middle. And that would be the worst thing in the world, either. Emily Oster: Absolutely. Yeah. No. It turned out with the second kid that was much easier. So, it was easier to follow through.

28:34 Russ Roberts: Let's talk about an area that some parents struggle with a lot; others don't struggle with at all. But it does engender a lot of controversy. Which is vaccines. What do we know about them? And how effective--what's the quality of that evidence? Emily Oster: Yes. So, vaccines are safe and effective. I spent a lot of time thinking about just how to talk about this in the book. Because I think that this has become such a controversial topic, and I, you know, I pretty firmly believe in vaccination. But I think that it is a mistake to just dismiss people who don't believe in vaccines, as crazy lunatics. Which I think is sometimes the attitude of the pro-vaccination community. And so, what I did in constructing that chapter was I went into--there's an Institute of Medicine Report, which is like 1000 pages long; and it goes through all of the data on links between vaccines and adverse outcomes. And I tried to read it--I mean, I did read it. It was long. And I tried to actually sort of drill in to some of what are the actually risks of vaccines that are identified in this, like, very carefully constructed report. And what are the things that are not risks. And so, you know, one of the things that comes out there is, like, there are many things for which we don't have data. You know, there are many things people have suggested as risks for vaccines where there is simply no evidence, that would be a risk. But, also, no evidence that it wouldn't be a risk. There just isn't any evidence or reason to think it would be a risk. Um, and then there are a few things where there are risks of vaccines. These are either very, very, very, very, very unlikely. Like, in the space of--there have been 3 episodes of something. And it is only a risk for immune-compromised children. Like, that's an example of something. Or, that they are pretty minor. So, some kids get a fever after the Measles, Mumps, and Rubella vaccine [MMR]. That's reasonably common. But also, not something to worry about. And then you can also go through some of the evidence on some of the things that get cited more frequently, like the links between autism and vaccines, where there's simply no evidence that vaccines cause autism. So-- Russ Roberts: Well, there is evidence. You don't think it's--it's not reliable. Emily Oster: There is tons of evidence that vaccines do not cause autism. Russ Roberts: Correct. Emily Oster: Huge amounts of evidence that vaccines do not cause autism. That is very well supported. There is a discredited paper that has been retracted, which was this sort of original source of that link. There is no-- Russ Roberts: We have an episode on that. I'll put a link to that. Emily Oster: Yeah. So, I think that people should vaccinate their kids. Some of my research is that, kind of more about why people don't. This isn't really in the book, but just thinking about some of the ways that we could encourage vaccines, given that the evidence sort of strongly supports them, and that we actually have kind of gotten into a position now where some things, like measles, actually the vaccination rates are so low in some areas that there are all real risks of outbreaks, and we are having, currently, in the middle of quite a large measles outbreak. Because people haven't vaccinated. Not enough people. Russ Roberts: And therefore? Emily Oster: And therefore people get measles. Russ Roberts: No, but and therefore you recommend? You think that the costs-- Emily Oster: I recommend that people should vaccinate their children. I recommend you vaccinate your children. Russ Roberts: So, by the way, you said it was like a thousand pages long? It was like a thousand pages long. Emily Oster: Yes. Russ Roberts: This is not like, long. It's like a thousand. It's like, 9-something, right? Emily Oster: Yes: 980 pages. Russ Roberts: Which doesn't make it true. We should be careful. But, you are thinking it was thorough. Emily Oster: It's thorough. I mean, I think that sometimes in these debates about vaccines you get the feeling that people think the CDC [Centers for Disease Control] is just standing on one side, being like, 'Oh, it's fine. Trust us. We're experts.' And then the anti-vaccination side can seem more evidence-based, because they are saying, 'Well, look at these papers. Look at this evidence that we have come up with.' And I think, you know, that's not right. The conclusions that the CDC is drawing, and these American Academy of Pediatrics is drawing from, these are really carefully researched. This is a thousand pages which reflects, you know, reviews of thousands and thousands for studies by many, many, many people over a period of many years. And, the conclusion is vaccines are safe and effective. But, it's not just something people are saying. It is something we have evidence for.

33:25 Russ Roberts: Well, I was just going to add a philosophical thought, which is that it's very hard to be cold and calculating about our children. It's very hard to be data-driven. We have lots of fears that haunt us--worries, anxieties, concerns. And it feels like life or death. You know, anything from--I'm just trying to think[?], in our own raising of our children--the time we ate some fish, when my wife was pregnant, that we thought it was from a lake rather than the ocean and maybe it had more mercury. Those kind of worries really keep you up at night. And I'm curious if, in writing these two books and being forced to concede, in some places--not all, but in some places--how uncertain the evidence is: Has it caused you to become more cautious in how you interpret studies that are not quite so life-and-death? Outside of the realm of child raising and pregnancy, and in more standard areas of economics? Emily Oster: Yeah. I mean, I think that this work in general, it's actually influenced my academic work a lot, because I've started thinking a lot more about issues of causality and how we--like, what kind of conclusions can we really draw from data, and when, how can we improve our ability to draw those kind of conclusions? But, I do think, particularly, for these realms of parenting and kind of choices people make about their health or the health of their kids, the evidence is often very limited. And really not very good. Or, you know, not as good as you would like it. And so I think that we're making a surprising number of decisions based on evidence that isn't what we might hope that it would be. And sometimes I've wondered: Why isn't the evidence better? So, going back to the question of breastfeeding, I said that there was like one randomized control trial. I continually wonder: Why is that? Like, this actually doesn't seem that difficult, to run another trial--with, you know, particularly in the United States where breastfeeding rates are not super-high. And so you could imagine doing the same kind of study here. And I'm always sort of curious why people haven't pursued that. So, why isn't our data better than it is? I don't know. Russ Roberts: Yeah, no: I'm curious if this has made you more humble as an economist in terms of policy prescription. I think we all know that the less humble you are, the more attention you get. So, humility is not rewarded in the marketplace of competition among economists generally. But has it helped you in thinking about these issues? Has it helped you become more humble in your policy confidence? Emily Oster: Yeah, it's interesting. It's an interesting question. Probably--I think part of it is I've started working--and I think this may actually be something of a reflection of what you're saying--I've started working much more on things which are more or less just descriptive, rather than saying, 'Because of this causal relationship we should do x.' So, I've become--my work, I think, has become more sort of saying, 'Look, here is an interesting relationship in the data that I think we could learn something from.' Which actually isn't, as you point out, always as successfully kind of research, because people like the sort of, 'Let's do x and y will happen'-- Russ Roberts: Yes, they do-- Emily Oster: But I think that, for many reasons, of which the books are probably one of them, I have moved into more of a, like, 'Here's something we see, and what could we take from this?'

37:30 Russ Roberts: We've had Bryan Caplan on the program, and Bryan is a very vocal advocate for having children, number one, which is not what your book is about. You don't deal with the question of should or should you not. But, Bryan also believes that one of the reasons you should have more children is that parenting is not very important. And, of course, as a parent, it's a lot of work. It's an immense amount of work. Don't worry--I'm going to come back later and defend parenting, as a general activity. But, it is an enormous amount of work. And, it can discourage you from having a child. And Bryan says, 'Yeah, don't be bothered by it. Whether you're good or bad at it doesn't really matter. The kid's going to turn out the way they're going to turn out regardless of what you do. And that would seem to be the kind of empirical question that would be almost impossible to answer. But Bryan claims to answer it. And there are papers and authors who advocate for the overwhelming importance of genetics, and sort of obvious things that aren't much work, like not letting your kid near a hot stove or raging traffic or and exposed electrical outlet; and the rest of it is just not that important. All this stuff: breastfeeding, co-sleeping: 'Nah, forget about it. It's all fine. It's going to turn out okay.' What's your view on that? Emily Oster: So, I think there's sort of two pieces of that. I think the claim that, sort of, parenting and the king of circumstances that people are raised in are not important for their outcomes belies a huge amount of social science about the importance of circumstance to outcomes. I think that you don't need to look much past patterns of inequality and persistence of inequality in the United States to think that it is a lot better to be born the child of Bryan Caplan than, you know, the kid of a single mom on the south side of Chicago-- Russ Roberts: I'm not so sure. Emily, I'm not so sure. Bryan--maybe you picked a bad example. Nah, I'm just teasing you, Bryan. If you're listening in, it's okay. Sorry. Go ahead, Emily. Emily Oster: But, you know, I think if we just look at--Chinese research on this topic it's hard to think that these patterns of inequality don't have something to do with circumstance. I will say, I think there's a separate question, which is: Once you are who you are, when we think about these more minor parenting choices, like breastfeeding versus formula, or co-sleeping versus not, or when do you potty train, or what kind of pre-school do you choose, I can more easily imagine that those kind of choices do not individually matter very much. And I think that there is some evidence, so of which I cite in my book, that most of these choices are not the most important thing that you will do. I think that, you know, the challenge is: As a parent, you are going to make these choices, and you want to make them in a way that you are happy with. So, I think in some sense, I would say it doesn't--maybe it doesn't matter which choice you make, but it's not good if every choice, you then feel like you didn't do it right. And I think that's kind of the key here: is to give people a way to think about these choices that they are happy with, because they feel like they've thought about them in a way that's kind of structured and organized. And that will make you happy. And that that will make you a happy person. And being a happy person is a good thing, even if it's something that makes you a better parent. So, that's kind of my take on those pieces. Russ Roberts: I think it might make you a better parent. I wouldn't discount that too much-- Emily Oster: that--I agree-- Russ Roberts: I do think anxiety is a very big challenge of parenting, and the insecurity and unease that I think modern parents have, I think, relative to parents of the past is a fascinating thing in and of itself. Part of it is due to the fact that we have smaller families. And part of it is due to the fact that we are probably wealthier. And part of it is due to the fact that we have too much information that we don't know how to process. Emily Oster: Yeah. Russ Roberts: And that last one is the one I think is most interesting. But, I want to move along.

41:51 Russ Roberts: One of the areas where you do come down pretty firmly on where the evidence lies is a fascinating story of economic and statistical detection, which is peanut allergies and the Bamba effect. Talk about that. Emily Oster: Yeah. So this is one of my favorite examples in the book. So, there were a series of studies. So, peanut allergies have gone up over time. In the sort of mid-2000s, there was a guy in the United Kingdom who wrote a paper in which he compared kids in Israel to peanut allergies among Jewish kids in the United Kingdom. And he showed that basically the kids in Israel were way less likely to have peanut allergies. And he attributed this--he kind of took the next step--and he said, 'I think that's because they get early exposure to peanuts.' So, there's an Israeli peanut snack which is like a very early food for kids. It's called Bamba. And so, his idea was like, 'They eat peanuts early, and the kids in the United Kingdom are advised to wait on peanuts. That early exposure is why they are less likely to be allergic.' Now, of course, as an economist-- Russ Roberts: It's ridiculous-- Emily Oster: I mean, cross-country studies--it's like, you know, this is like we are in the 1980s. You know, we're not into that. But then they actually went a step further and they ran a randomized control trial, in which they took kids--actually, they started with kids who were at higher risk for allergies in the first place so they could have enough power, enough sample size, in the study. And they exposed some of them to peanuts early, and some of them to peanuts later. And they show that the kids with the early exposure are way less likely to develop allergies than the kids who didn't have exposure until later. And that happened even for kids who initially had a low risk of allergies, but also for kids who initially had a very high risk of allergies. And these effects in the study are, like, extremely big. So, for the kids who had sort of a high allergy risk initially, like they showed some peanut sensitivity. The kids who did not get exposed, but a third of them ended up with a peanut allergy. Versus 10% in the group that had early exposure. So, that's like a huge effect. And, of course, the thing that is, like, very disappointing about this, in some ways, is that people have been told not just--it's not just that they have been told, that they have not been told to have early exposure, but actually the advice until very recently-- Russ Roberts: Was, 'Stay away.' Emily Oster: Was to stay away. Which actually made this problem worse. So, it's like, then many, many kids have peanut allergies now, many more than in the past. And it may well be due to this basically wrong advice. And then it turns out this actually is true of many other allergens. So, there are a few sort of key things that people are allergic to, wheat, eggs, milk, peanuts being sort of the main ones. And it turns out for most of those, there's now evidence that exposing kids early is good for preventing allergies. Russ Roberts: And, of course, one has to be always careful. It could be this was a study sponsored by the Bamba Institute of Israel or the American Peanut Farmers' Association [sic: imaginary association name given by Russ as an example--Econlib Ed.]. You should always be a little bit skeptical. But, it does make some sense. Which is good--it passes the sniff test--that, the rising growth in peanut allergies could be due to some environmental change, which is: Not eating peanuts when people are young. And it goes back to, you know, a very interesting episode we had a long time ago about the rise in auto-immune disorders and the question whether we are too clean, whether we are too hygienic. Which seems like a good thing. But, if you don't develop those pathways in your body that keep you safe, maybe you should be eating more dirt when you are young. Or, playing in the dirt, or whatever. Emily Oster: Yeah. I like my kids to eat a lot of dirt-- Russ Roberts: Heh, heh, heh. Emily Oster: There you go-- Russ Roberts: Careful-- Emily Oster: Yeah. So, no; I think there is, the sort of body of evidence now around this is pretty compelling in favor of the early peanut exposure. Russ Roberts: Yeah. That episode was Moises Velasquez-Manoff. Which is interesting. Could be true.

46:15 Russ Roberts: Let's look at--I don't want to forget that the very first episode of EconTalk, which was a little more than 13 years ago, was on parenting. With Don Cox. It's called 'The Economics of Parenting.' And it's before we adopted the nomenclature of 'Don Cox on Parenting,' which it should be called. But in that episode, Don uses economic principles. And, the first part of that conversation, which is a mere 34 minutes--also before we started doing hour-long--Don explains why you should put your kid's coat on outside rather than inside. Because your kid's going to be cold: 'You're going to want to put your coat on.' But, one of the issues that you deal with in the book, of course, is the challenge of-- Emily Oster: Mmmhmmm-- Russ Roberts: You like that? Emily Oster: Yeah. I like that. I do like that. Russ Roberts: I do, too. And snow pants, too--you recommend. Because they are hard to get on; and the kids kind of fight you. And-- Emily Oster: No, no. It's true. I am always having that argument with my children. I'm going to keep that in mind. Russ Roberts: So, there's a general issue, of course, which is discipline, and how to deal with kids--who, strangely enough, don't always want to do what you want them to do. And I thought this part of the book, though probably not as scientific as some of the others, was fantastically great. So, talk about what we know, to the extent we know it, about discipline. Emily Oster: Yeah. So, there are some--this was actually, I will say, confess, this was not a part of the book I intended to have in--because, I don't know--when I first conceived of the book I didn't think that science would have any, much, to say about this. But my editor pushed me. She said, 'Look, I really want to know the answer to this. Can you please try to figure out if there is anything about this? And if there is, we can put it in.' And so, it actually turns out there's more science on this than we might think. And, [?] are some randomized evaluations of a sort of particular kind of discipline program. It has a lot of different names. So, one of them that's well-known in the United States is 1-2-3 Magic. There's something called Positive Parenting. These all have kind of the same principles, which are just that you should be very, very consistent in discipline. And that, when you discipline your kids, you have to remember that they are not adults. And I think this is the part that is in some ways really challenging-- Russ Roberts: Deep revelation! But,-- Emily Oster: Deep revelation. Yeah, but like-- Russ Roberts: You'd think it wouldn't be. But it's big. Emily Oster: It is. Because, in the moment with your kid, and they won't put on their snow pants, it's just like: 'What is the matter with you? It's cold outside. I can literally see the snow outside.' Like, 'Why are you not listening to me and putting your pants on?' And, you know, you are sort of having this reaction; I think that a lot of these are about looking as a parent: The first step of discipline is to step back and not get mad. And not yell at your kids. Because that's not effective. Because, who knows what's going on inside their head? It isn't that they are thinking, 'It's snowing outside, therefore I must put on my snow pants otherwise I will get wet.' They are thinking something else: 'I don't want to put the snow pants on. It's hot in here. My foot is itching.' Who knows-- Russ Roberts: I'm hungry. Emily Oster: 'I'm hungry.' Like, they are just--they are not an adult. And I think, so these things all sort of start with the idea of just sort of recognizing that your kid is not an adult; and that, also discussing it with them is not helpful. And so I think, for me, that was actually a big revelation in reading these things. Because, my kids are pretty verbal. And so there's the temptation to want to explain to them-- Russ Roberts: Dialog-- Emily Oster: Yeah. Have a negotiation. So, 'Can you tell me how you are feeling about the snow pants?' Because, the thing--but then, it's like, well: What does it matter, how they are feeling about the snow pants? You've got to put the snow pants on to go outside. And so, these discipline systems sort of emphasize, kind of, not getting angry. And then also having a structured set of consequences for particularly bad behavior. So, not so much for snow pants but for things like, you know, 'Don't put that thing in your mouth'; they do it anyway-- Russ Roberts: or in your brother's mouth-- Emily Oster: or in your brother's mouth. Or, 'Don't pull your brother's hair,' or 'Don't pinch him on the cheek that many times.' And sort of, a structured set of consequences where you have, you know, warnings and then some consequence like a time-out. But, in all of these things, you know, the main things they are emphasizing are consistency and not getting mad--that adults should try not to get mad in the moment. Which is, of course, very easy to say when you are writing a parenting book and very difficult to do when you are actually parenting. But we can all aim towards that. Russ Roberts: Talk is cheap. But I think what's fascinating to me is these principles--you don't need science for 'em. I think, in the cold light of non-child day, of your child not being in front of you, these are pretty obvious. Don't make a threat you are not going to follow up on. Emily Oster: Yes. Russ Roberts: Parents do it all the time. Emily Oster: Yeah. No, when I was writing this, I was, then, I was writing this and I was on an airplane, and somebody behind me, like the kid, her kid was kicking the seat. She said, 'If you kick keep doing that, I'm going to leave you on the airplane.' That is like a classic example of a threat that you shouldn't make. Of course you are not going to leave the kid on the airplane. Russ Roberts: The kid notices, too[?] Emily Oster: You have kicking. She took him off the airplane. And so you've got to sort of--someone is not thinking about, are you willing to follow through on the threat that you are making. If you are saying, 'We're going to turn the car around,' that's okay. But you've got to be willing to turn the car around. I think that's hard. Russ Roberts: So, these rules, which I wrote down from your book: Don't discuss. Don't get angry. Clear consequences and consistency. They are kind of obvious, again, in the abstract. But in the moment they are a little bit harder to implement. And I think that's fascinating. I think one of the challenges of non-negotiation was that I think we believe, often, perhaps correctly but probably not, that if we talk it out with our child, they'll become smarter. They'll learn that it's cold outside, and they can get sick. And, at the age of 2, 2-and-a-half. And I think that's a mistake. To bring Don Cox back into the picture, he had to deal with his kid that when the kid said 'Why?'--which seems like a great question, you know, for a parental dictum--Don would say, 'Well, I'll tell you why, but I want to make it clear from the start that it's not going to change what we do.' And the kid would go, 'Yeah, okay. Whatever.' It's not an educational moment for them. It's a strategy. Emily Oster: That's funny. I like that.

52:45 Russ Roberts: Let's talk about something dear to my heart, which is reading. I have a joke that before I got married, before I had children, I would read a book a week. And after I had children, I would read a book a night--but it had a lot more pictures. And of course, after a while I was reading 2 or 3 books a night with a lot of pictures. And, we believed--it was a wonderful experience. It was a rule that was hardly, if ever, broken. We always read a book to our kids before they went to bed. And I suspect, even though we loved it, there were times when--my wife, for example, Curious George was not her choice; and she was stuck with it; and I would maybe come in and help her. Or she'd just push through and read it even though she didn't love it. Because, I think deep down she thought, 'Reading to our kids is good.' Is it true? Emily Oster: Yeah--I think the evidence would suggest yes. This is a place where it's really hard to learn all that we would like to from the data, because reading to your kids is really heavily associated with other kinds of features of parents like education or income, which also have good outcomes or have associations, rather, with good outcomes. And so--but, I think there is some evidence around the value of reading, some of which comes from differences in spacing between kids and looking at first kids where there is more space before their younger sibling is born. So, there is sort of more concentrated parenting time. And one of the things that happens if you have more time with just one kid is you read to them more. And that does seem to have some positive impacts on, like, reading readiness and reading performance later. There's also some kind of need--I wouldn't describe this exactly as evidence in favor of reading, but there's some interesting science--like FMRI [Functional Magnetic Resonance Imaging] research, where they put kids in FMRI machines and they image their brains when they read to them. And so, this, so what they find in this particular very small study is that kids who have more reading at home, when they are read to in the machine, there is kind of more activation in parts of the brain that's associated with imagery. So it sort of seems like maybe they are having an easier, they are like having more of an experience of kind of seeing the book. Again, that's like one of these, like, 'Ooh, that's interesting' facts, as opposed to something that says you have to read to your kid. It does look like reading is mattering some, up to the limitations of the data--which are very real, in this case. Russ Roberts: Yeah. I think the main reason to read to your kid is you enjoy it. Emily Oster: It's fun. Exactly. Russ Roberts: And if you don't, you're probably not going to help them much. It is a--it's to some extent, a matter of taste. Having said that, I think the more interesting question would be whether it builds a taste for reading. I like to think it does. I don't know. It's really hard to measure. Emily Oster: Yeah. For me, it, like--I love books so much that it was always something where it's just, 'I want to be reading to my kids, because this is some that I like,' and that I like to do. And now that my daughter is old enough to read stuff that I really enjoy reading, it's even more--it's even more fun to get to do it. So, for me, that was--most of the motivation was just that it was fun and it was something we could do together that I enjoyed more than some things like building with Legos--which was never my thing. Not my taste. Russ Roberts: And it's something you share for the rest of your life. Which--I don't build that many Lego stuff with my post-adolescent, college-age kids. Which is maybe down the road. But, we talk about books pretty often, which is fun. Just a consumption good. We like to think it's an investment good.

56:56 Russ Roberts: So, I'm going to ask you about something that's, um, a little bit metaphysical, maybe philosophical. I got into a really interesting conversation on Twitter with Julia Galef, who is the host of a podcast, Rationally Speaking. And she said, 'You know what we need? We need'--I hope I'm doing her justice here; this is what she said, something like this, 'We need 10,000 people who are thinking of having kids, and we'll follow them over the next 20 years. And some of them will, and some of them won't. And we'll interview them and find out whether they were glad, happy with what they did.' And, I suggested that was not a good strategy. For a bunch of reasons. And, this generated an enormous argument on Twitter between people who thought, 'Well, okay: Sure, it will be a flawed study. But some data is better than nothing.' And my view is, often, that: 'No, it's not. It actually leads you to think that you know something that actually you have no idea about.' And when I think about the question of whether to have children--which, you touch on indirectly when you talk about its effects on marriage, which is a very interesting chapter--but when I think about the question of whether to have children, I don't think of it as a cost/benefit analysis. I never did. I still don't. And I don't recommend that people do that. For starters, you are a different person after you have children than before. So, it's really hard to know how to weight what somebody says after they've had children. Um--they are not like you. They are at a different stage in their life. Happiness isn't the only thing I care about. I'm not sure what to do with the self-reported number. There are just so many things--and I look at that--and, for me, the reason I have children, it's an extremely, enormous part of the human experience. Period. And you should, if you can, unless you have strong reasons to not do it--which you could, for all kinds of emotional or physical reasons--it's something to experience. Because it's part of being human. So, that's my simple argument. I don't use data. You know, I could invoke some. I suspect that if you survey most parents, they are glad they had children. But I don't put much weight in that. And if they said they didn't, I wouldn't put much weight in that, either. What are your thoughts on that general question: on those kind of big issues and that particular one? Emily Oster: Yeah. I mean it's very--I think, so, I'm with you on this sort of first question of, 'Could we learn much from a study which compared people who had kids to people who don't,' because that choice is so--it's sort of so endogenous and so carefully thought out that I don't think we would learn much there. I think the experience of having children is so varied; and I think happiness is such a funny way to think about it. I mean, we see these studies where you sort of ask people, 'Are you happy?' Like, in the moment. And a lot of times, in the moment of being with their kids they are not necessarily that happy. Particularly with little kids, because they can be tiring and frustrating. And, you know, when you are trying to get them to put their snowpants on, it's not like the best part of your day, always. But, then when you ask people about sort of the experience of having kids, most people will tell you, like, you know, 'This is the best thing that I do.' And so, I do think it's hard to--I mean, I find happiness in general is a hard thing to think about, and particularly around your kids, where it's so--like, once you have a kid, as you say, you are sort of a different person; and there's, all of a sudden, this part of you that is so much more important than anything else, that you are doing, anything else that you are experiencing, it's hard to--it's just hard to think about how you would ask, 'Well, what would I feel like if I didn't have them?' Once you have them, that's a totally different question than if you sort of don't have any yet. Russ Roberts: Yup. Yeah, and I think about the fact--I'll never forget this--after we had our first child, I'm at the movies, and it's a different experience. And I don't mean because I'm worried about, you know, the babysitter or, in this case, I think the kid was sleeping while nursing with my wife in the theater. I think she was probably, you know, 6 weeks old and we were out for the first time-- Emily Oster: I can't believe you went to--I don't think I've been to a movie in like 9 years. Russ Roberts: No, you [?]. It took us a while to figure this out, by the way. It's that, if you are going to get a babysitter, you better at least go to a show. Because-- Emily Oster: Right. Because--what is the point? You can watch a movie. And you-- Russ Roberts: It is not as good. But it's close enough that the baby-sitter thing--of course, it's getting out. It's complicated. It's still--but you are different person. It's not just something you care about. Your head becomes different. And, it's a scary thing. I understand why people struggle to make the leap. There's a video that I think it's Gretchen Rubin made, that's really absolutely beautiful, called "The Days Are Long and the Years Are Short." The people--parents tell you--and I hate this parenting remark, 'Oh, it goes by so quickly.' And, when you are in the middle of it, it doesn't. Emily Oster: It doesn't feel like that. No. It does not go by that quickly. Russ Roberts: No. It's eternal. That night, that first night of crying is not going quickly. It's unimaginably long. And yet there's this weird paradox that the days are long, but the years do go by somewhat quickly. Which says, you should say, some, if you were a parent, you should notice them and try to be present for the, again, that human experience: Not because your kid's going to happier, richer, or more successful, or more adjusted. It's just part of life, and you should be there for. Emily Oster: I totally agree. Could not have said it better.