I find slightly different numbers from different sources but they are all pretty close to around 1600 square feet in 1970 to 2600 square feet in 2016(last year listed).

The number of houses with two or more bathrooms has gone from 30% to 80%.

https://www.aceee.org/files/proceedings/2004/data/papers/SS04_Panel1_Paper17.pdf

I listened to it a while ago but that sounds similar to what he ended up doing.

Malcom gladwell did an update on his podcast and observed that many parents are using his data as a reason to hold their children back a year to give than an academic advantage.

He’s done an update on his podcast recently. Now some parents are using his data to intentionally hold their Children back a year to give them an academic advantage. Enough to start skewing the data.

Edit - I don’t think gladwell came up with this idea but he did make it more mainstream.

What is pseudoscience? Body fat? Skinfold caliper tests? Being overweight is unhealthy?

There was a group of doctors who got sick of hearing “BMI doesn’t apply to me because I’m so muscular”. So anytime they heard that they pulled out the body fat calipers. The vast majority of these patients had unhealthy levels of body fat.

Edit - I can’t find the article and don’t remember the specifics but the main takeaway was of people who claimed BMI didn’t apply to them the vast majority where overfat.