I remember taking the bus with my daughter when she was two or three years old. An older woman saw me with her, chuckled and said, "Oh! You're babysitting today, eh?"

I was used to people thinking I was an older brother or something (everyone thought I looked too young to be a dad), so I explained, "No, this is my daughter."

She just nodded and said, "Doesn't matter. You're babysitting."

I thought about explaining that I was a stay-at-home dad, the primary caretaker of my daughter and had been since she was born. I wanted to tell her that my wife and I had made the decision long before her birth for me to stay home with the kids, and that this wasn't a temporary, "until I find a job" situation. And, no, I was not babysitting.

Fast forward to the present. Just the other day, I was upstairs when I heard the doorbell ring one afternoon. Figuring it was a UPS delivery that was just left on the porch, I took my time, and then I heard my older daughter open the door. A man's voice said, "Hi! Where's your mom?"

"She's at work."

I was heading downstairs, thinking that the guy would ask who else was home, but instead he just said, "Okay. Guess I'll come back later." And left. After I explained to my daughter that she should check with me before opening the door to strangers, she wondered aloud why some guy wanted to know where her mom was. So I had to tell her that, well, a lot of people just assume that the mom is the one who's home with the kids, and it doesn't occur to them that dads might be, too.

So it was with some interest (and, I'll admit, not a little irritation) that I discovered these assumptions aren't just held by your average, stuck-in-the-1950s, unenlightened citizen. The U.S. Government thinks so, too. I was surprised to find that my duties as a stay-at-home dad are considered "child care," according to the Census Bureau. But that's not all: "Designated parent" is defined as the mother, unless the child lives with the father in a single-parent household. And if the father works and the mother stays at home with the kids? Well, they don't really count that time at all as "child care" – it's not really considered in the equation.

On Wednesday, the New York Times' Motherlode blog talked about the bureau's "Who's Minding the Kids?" report, which you can download as a PDF. The report itself is, as you might expect from a governmental report, somewhat dry and boring. But buried within it are some assumptions about parenting and gender roles that I find extremely problematic. By definition, the "designated parent" is the mother if both parents are present in a household, or in single-mother households. In a single-father household, the father is the designated parent. They ask the designated parent questions about child care. "If the mother is not available for an interview, the father of the child can give proxy responses for her." Ah, that's good to know.

I emailed Lynda Laughlin, the author of the report, to ask her a few questions about how child care is measured, why certain things are taken into account but others aren't. Here's part of her explanation about the Survey of Income and Program Participation (SIPP), from which the data was taken:

In SIPP, child care that is provided by the father, or more broadly the other parent of the designated parent, is only asked of designed parents that are working or going to school. For the purposes of SIPP, designated parents who are working or enrolled in school are asked to report what type of child care they use while at work or school. For designated parents who are not employed or enrolled in school, we ask who cares for their child while the child is not in their care. The aim of the SIPP survey is not to measure "parenting" per se, but more to measure who is minding the children when they are not in the direct care of the parent either because she/he is working or is engaged in some other activity.

So, according to the SIPP, if you're a mom and the father is at work, you aren't "minding the children." You're the designated parent, so whatever time you spend caring for your child is, well, the norm and isn't measured. If you care for your child while you're working or at school, then those hours are counted. And if you're a dad, the only time counted is when the child is with you exclusively – as soon as mom is home, your time is no longer measured, either.

This leads to some interesting statistics. For instance, in Table 1 of the report, "Preschoolers in Types of Child Care Arrangements," you'll find that of the 63 percent of preschoolers who are in a regular arrangement (meaning some arrangement that was used on a regular basis, at least once a week), 4.2 percent are cared for by their moms, and 15.2 percent are cared for by their dads. Wow, really? Nearly four times as many preschoolers are regularly cared for by their dads than their moms?

Well, sure, if you don't count the time moms spend with their kids while they aren't working.

Or take my personal case: Since my older daughter is in elementary school and spends roughly eight hours a day there, she's home with me for about, say, four hours a day when mom isn't home. (A little longer on days when mom's in evening clinic.) Since my time is only counted when mom isn't home, this means that I'm not considered the "primary arrangement" for child care, despite the fact that I'm the one who packs her lunch, gets her off to school, checks over her homework, takes her to her violin lesson, cooks and feeds her dinner, and does her laundry. When you find that only 7 percent of dads provided "the most hours of care" for their school-aged children, that 7 percent doesn't include full-time stay-at-home dads like me. Presumably that's guys whose wives work evening shifts and aren't at home in the evenings, or single dads who do all the child care.

Laughlin also included this bit of info:

While data on designated parents who are the father (i.e., a single-father household) is available from SIPP, our published tables and reports focus on mothers who are the designated parents because the number of designated parents who are the father is a very small sample and would lack statistical reliability.

Well, sure. If you specifically limit the definition of "designated parent" to moms and single dads, then you're going to have a smaller sample of "designated parents who are the father." I freely admit that the percentage of stay-at-home dads is quite small. It's not a big group, and I sort of understand that it may not be statistically significant. However, I find it ridiculous that large swaths of time that mothers spend with their kids are entirely unmeasured and ignored by the SIPP because of this definition of "designated parent."

Once more, from Laughlin:

SIPP surveys over 35,000 households and from that data we need to accurately represent the nation as a whole. While the data and specific methods used to acquire this data may not accurately represent your household, the data does help us understand child care usage patterns among families in the United States.

Until the Census Bureau can actually figure out how much time moms and dads actually spend taking care of their kids, I sincerely doubt their ability to "accurately represent the nation as a whole." I think the SIPP does a disservice to both dads and moms, perpetuating stereotypes and writing off anything that doesn't fit conventional gender roles.

Now, if you'll excuse me, I have a sick child who's home from school today. I'll need to go provide some child care since the designated parent is away on a business trip.