What women do to a President

The previous post got me thinking: Can daughters also explain the party of the President of the United States?

To find out, I got data on all US Presidents since 1945 from Wikipedia and fit them on a linear probability model. My dependent variable was the party of the President and the difference between daughters and sons the regressor.

The results? Having an extra daughter increases the probability of a President being a Democrat by 1.7%.

Now, my initial dataset is not free of problems. Reagan had the highest number of daughters of any Presidents (four), and thus messes up with the results significantly. But Reagan, of course, was a Democrat during his early years in politics. Correcting for this fact, 1.7% jumps to a more respectable 9%.

Good going so far, but of course there's more to it: my model does not account for intergenerational effects. Assuming that parents also have an effect on their children's voting behaviour, George W. Bush should clearly be excluded - his dad had no less than 4 sons. This leads us closer to the true value of the probability in the population - a by now very convincing 13%.

But this is not enough to establish causality - we also have to make sure our results are robust. To test for this, I add an additional observation to the dataset excluding W Bush and with Reagan labeled a Democrat. Enter President Jed Bartlet, Abu el Banat, father of 3 daughters, the fictional President of 'The West Wing' - the award-winning TV series. If our model's specification is correct, including President Bartlett should not affect our results, since he is not for real. Indeed, his inclusion returns us an estimate statistically equal to 13% - a clear sign that our model does a good job capturing the true effect of (real) daughters.

While more research is necessary to broaden the evidence base and explore other interesting hypotheses, the results here are very promising. So now you know: next time you come across a rising political star with daughters, chances are he's a Democrat.

Disclaimer: This post is meant as a joke, please do not take any of this seriously. I'm enjoying a lazy weekend.