Assume we have a lot of observations, like the height and weight of every person in a group, or the time of visit for every visitor to a website.

Lots of data is hard to visualise, so we usually group the data in equal intervals (bins) and count the number of observations in each bin.

The chart below shows the heights of 25,000 eighteen year olds grouped in one inch intervals.

The workbook available here shows how to do this with a couple of simple formulas. We use COUNTIF to count the number of observations greater than a certain height, and take the difference between successive values to count the number of observations in each interval.