Chapter 6 Percentages of a whole

Percentages of a whole are a very basic measure of just how much of the whole a thing represents. It’s a very simple measure, but one often confused by the less numerate. The trick is to just remember that it’s simple. The basic formula is this: The thing you are interested in that's part of a larger whole / the larger whole or more compact Thing/Everything

6.1 How to calculate a percentage

Let’s look at the students in colleges at the University of Nebraska-Lincoln. Every year, the university performs a census of students across campus shortly after classes start. That census produces tons of data, but one of the most interesting is the students by degree, major, race and sex.

There are scores of stories in the overall data broken down to each major, but for simplicity, let’s look at the colleges. More specifically, let’s ask this question: Which college has the greatest gender imbalance?

6.2 How to calculate a percentage in a spreadsheet

In the dataset, there’s 10 colleges – 9 actual colleges and one called Explore Center, which are how undeclared students are grouped together. It’s included because it’s larger than three colleges.

Open the file – you can download it here – and in Column W, Row 1, let’s add a new header called Percentage Male.

Then, in Column F Row 2, let’s calculate our percentage. So we want to take the subset (male students in this case) and divide it by the total (the column labeled Total). So our formula will look like this: =U2/T2

Really, that’s it. Copy the formula down by double clicking on the notch on the bottom left of the cell. Now sort it largest to smallest (descending order). What do you get?

6.3 How to turn a percentage into a story

Percents of a whole end up in stories all over the place. In the case of our student data here, I’d want to know why. Why does one college have far more men than women, or vice versa? What attempts are there to recruit women into male dominated fields? What efforts are there to recruit men into female dominated fields? What’s driving this? And (looking to the topic of the next section) how has this changed over time?