Archive for February 2016

Confidence Intervals for Medians and Percentiles

Medians are better than means in most interpretation contexts: they’re not affected by skewed or otherwise non-normal distributions. They give a better sense of the “typical” data point. When the mean and median differ, I prefer to use the median.

One problem with using medians is that you can’t calculate a confidence interval for them the same way as you calculate one for a mean. There’s no “standard error of the median”. However, it turns out there is a way to calculate confidence intervals for them. Continue reading ‘Confidence Intervals for Medians and Percentiles’ »

Defining Cause

It rained today and I didn’t have an umbrella, so I got wet. Why did I get wet? What caused me to get wet?

Suppose I was in LA during a drought and it was a weird, one-off shower. You’d say that I got wet because it rained.

Suppose I was in Seattle during an especially rainy season and, uncharacteristically, I forgot my umbrella. You’d say that I got wet because I didn’t have an umbrella.
Continue reading ‘Defining Cause’ »