After noticing this from a recent Pew Research report:

Ben Hanowell wrote:

This made me [Hanowell] think of your critique of Case and Deaton’s finding about non-Hispanic mortality. I wonder how much these results are driven by the fact that the population of adults aged 65 and older has gotten older with increasing lifespans, etc etc.

My collaborator Jonathan Auerbach looked into this and found that, in this case, age adjustment doesn’t make a qualitative difference. Here are some graphs:

Percent of adults over age 65 who live alone, over time, for women and men, with solid lines showing raw data and dotted lines showing populations adjusted to the age x sex composition from 2014:

The adjustment doesn’t change much. To get more understanding, let’s break things up by individual ages. Here are the raw data, with each subgraph showing the curves for the 5 years in its age category:

Some interesting patterns here. At the beginning of the last century, a bit less than 10% of elders were living alone, with that percentage not varying by sex or age. Then big changes in recent years.

We learn a lot from these individual-age curves than we did from the simple aggregate.

In this case, age adjustment did not do much, but age disaggregation was useful.

Jonathan then broke down the data by age and ethnicity (non-Hispanic Black, Hispanic, and non-Hispanic White; I guess there weren’t enough data on Other, going back to 1900):

To see people blogging about it in real time — that’s not the way science really gets done. . . .

Seriously, though, it’s cool to see how much can be learned from very basic techniques of statistical adjustment and graphics.

And maybe we made some mistakes. If so, putting our results out there in clear graphical form should make it easier for others to find problems with what we’ve done And that’s what it’s all about. We only spent a few hours on this—we didn’t spend a year, sweating out every number, sweating out over what we were doing—but we’d still welcome criticism and feedback, from any source. That’s a way to move science forward, to move the research forward.

P.S. I sent this to demographer Philip Cohen who wrote:

There are two issues with 65+: 1 is they are getting older, 2 is they are getting younger since the baby boomers suddenly hit 65.

Here’s a post by Cohen on this from a couple months ago.