Predicting Dichotomous Outcomes I

We are trying to predict a dependent dichotomous variable (male/female, yes/no, like/dislike,etc) with independent “predictor” variables. Let’s say we want to determine whether or not an employee will quit based on the percentage of their tenure spent traveling. We assemble the data from HR and erroneously employ simple linear regression to model the relationship, a […]

Layman’s Random Forests

I’m not a fan of the Top 40 style content on Quora, but a student in Dr. Leek’s Coursera class shared this absolute gem from Edwin Chen. I have not seen a better explanation: How do random forests work in layman’s terms? Suppose you’re very indecisive, so whenever you want to watch a movie, you ask […]

Unknown Variance Two-Tailed Test of Population Mean

Question The mean safety audit score of ACME Co. stores in New York (n=200) was 74.3pts February last year.  Suppose we decided to sample 22 out of the 200 stores one year later. We find that the sample mean is 78.6pts and the sample standard deviation is 3.2pts.  Can we reject the null hypothesis that […]