I’m sure this headline isn’t unfamiliar, as it’s been everywhere for the past couple of weeks:

Just 20 Minutes Of Weekly Housework Boosts Mental Health

Let’s have a bit of a look at the study behind the headline.

First:

any form of daily physical activity was associated with a lower risk of distress, when other influential factors, such as age, gender, and the presence of a long term condition, were taken into account. (emphasis mine)

They’ve made the usual error, confusing correlation with causation. Does the study show that physical activity causes increased happiness? No; it’s just correlated with it. The more active you were, the lower were your odds of being classified as depressed in this observational study. It could be that exercise causes happiness, sure. But it could also be that happiness leads us to be more active. This is a very basic point and it makes me crazy that even a science-oriented publication such as ScienceDaily regularly falls for it.

And second:

The range of activities, which proved beneficial, included housework, gardening, walking, and sports, although the strongest effect was seen for sports, which lowered the risk of distress by 33%. (emphasis mine)

So why the focus on housework? Oh, right: if we focused on sports as the most beneficial, we wouldn’t be able to get in that not-so-subtle dig at women — “See? Do housework, be happy!”. And to that I say pthththtthththbtbbbbt.