The first time I took a statistics class I was mystified with z-scores. I understood how to find a z-score… Read more
Category: Probability
Understanding qq-plots
qq-plot is short for quantile-by-quantile plot. You plot one quantile against another and you see if their coordinate pairs form… Read more
Independence vs. Mutually Exclusive
I used to tutor undergrad students in statistics when I was in grad school. One question that almost every student… Read more
The forgetful exponential distribution
The exponential distribution has the quirky property of having no memory. Before we wade into the math and see why,… Read more
Investigating the chi-square test of independence
Survey a random sample of 500 men and ask if they have seen Star Wars more than twice. Survey 500… Read more
Fume Cupboards
I was reading one of my favorite statistics books, Principles of Statistics, and came across a fun problem I decided… Read more
How many rolls of a die to see all sides at least once?
Say you have a fair die. (Most of them are these days.) You roll it once and observe a 3…. Read more