confidence intervals

Percentiles are order statistics. This means they’re determined by ordering observations from smallest to largest and then finding the value below which some percentage of the data lie. The most common percentile is the median. It’s simply the middle value (or the average of the two middle values if there are an even number of observations). Fifty percent of the data lie below the median. Other percentiles frequently of interest are the 25th and 75th percentiles. These are the data values below which lie 25 and 75 percent of the data, respectively.

Bootstrapping is a statistical procedure that utilizes resampling (with replacement) of a sample to infer properties of a wider population.

Say it with me: An X% confidence interval captures the population parameter in X% of repeated samples.

In the course of our statistical educations, many of us had that line (or some variant of it) crammed, wedged, stuffed, and shoved into our skulls until definitional precision was leaking out of noses and pooling on our upper lips like prop blood.

Or, at least, I felt that way.