3.5 Conditional Means

Another thing we can do with factor variables is to find how the average of one variable (e.g., our outcome- the callback rate) varies across different categories of our factor variable. For this, we use tapply().

## take the mean of input1 by categories of input2
## mean of call by race
tapply(resume$call, INDEX=resume$race, mean)

##      black      white 
## 0.06447639 0.09650924