Formula to subtract the average of a subset from a data column?
I am looking for a way to take a subset of a data table that uses only rows matching a specified condition, and subtract the mean of those rows from a column. For example, using the Big Class data set, say I want to create a new column showing "Difference in height between this student and the average 14-year-old of the same gender." The way I know how to do this is by adding a second table, usin...