**Pie in a Pie Chart**

This page concerns what Excel calls a Pie in a Pie Chart, which looks like this:

I have called this a 2 Pie in a 4 Pie for a reason that will become clear in a moment.

What we will see here is what a pie in a pie (pip) chart is

- how to construct one
- how many slices will be combined in the final slice
- how to take some control of one and
- how to use one to communicate data

We will also consider some additional points that you should find useful too.

I have to say at this stage that some people absolutely loathe pie charts. However, other people don’t!

**What is a Pie in a Pie Chart?**

A pip chart is a double helping of a pie chart:

- The pie itself which, however, combines one, two or more of the data points, depending on the total number of data points in your series
- A subsidiary pie which explains the detail of the combined series

In the pip chart in the introduction we see what I called a 2 Pie in a 4 Pie chart: in this case there are four data points in the series and Excel has chosen the final two data points in the series to combine into one slice in the pie on the left. Those two points are then shown on the right of the diagram.

The pip element of the pip chart, the right hand part of the diagram shows the combined values in proportion to each other: the Pie % in the table below. That means, in the case of the example above, that the two combined data points of 24.78% and 18.58% respectively are shown in the pip element as 57.14% and 42.86% respectively: the Comb % in the table below.

Take a look at the Excel file that accompanies this page where all of these values are clearly set out for you:

**Constructing the PIP Chart**

Drawing a pip chart is the same as drawing almost any other chart: select the data, click Insert, click Charts and then choose the chart style you want. In this case, the chart we want is this one …

That is, choose the middle of the three pies shown under the heading 2-D Pie. That’s it! That’s all you do.

Excel will tell you how many of the slices are to be combined together, which are then shown as the right hand element of your pip chart set up.

**How Many Slices will be Combined in the Final Slice?**

At first you might be mystified at how Excel decides how many data points it should combine in the final slice of the initial pie: the pie on the left of our pip diagram. There is a pattern to it, though.

With a little bit of experimentation I found that a pie with four data points will give us the 2 Pie in a 4 Pie chart. You will get a 3 Pie in a 7 Pie chart and a 4 Pie in an 11 Pie chart. I then used trendline analysis to find in general as follows:

These are the starting points of our slices: for one and two data points, there will be a combined slice; for 3, 4 and 5 data points there will be 2 combined slices; for 6, 7 and 8 data points, there will be 3 combined slices. And so on.

**Please note**: I used the trendline for this and it MIGHT be inaccurate here and there but I don’t think so!

**How to Take Some Control of Your pip Chart**

When you just enter some data into your worksheet and then create your pip chart, Excel just gives you your pip chart. It doesn’t take the largest numbers of the smallest, it just takes the last one or two or three data points and combines them.

Fine! At least we know what it is doing! How can that help us though? It can help in this way. By sorting the data, your combined slice will automatically contain the 1, 2, 3 … smallest values. Good.

Suppose you don’t want the smallest values but you do want, for example, data points bbb, ddd, ggg in a 3 Pie in a 7 Pie example? Well, just put them in the final three places in your data range. I know, not so smart; but it works!

Consider the next section, how to use your pip chart to communicate data now to take things a little bit further.

**How to use Your pip Chart to Communicate Data**

I am sure there are many ways of using your pip chart to communicate data effectively. Here’s one way I have thought of, following on from the previous section. You can do what I said there, force data points bbb, ddd and ggg into the final three places in your data range. Do the same for, say, the ranges aaa, ccc and fff … keep doing that until you have explored each pip …

**Additional Points**

I have only shown one kind of pip chart here. Here’s another one:

In this case, it’s still effectively a pip chart but they have turned the smaller pie chart into a set of bars of columns instead. Just as good or bad, don’t you think?

Imagine you want to show the detail of eight data points in the smaller chart but you don’t have the 22 data points you need for Excel to provide them for you. There is a way! Create dummy, empty, data points to make sure there is a total of 22 data points in the range for your pip chart. Then drag the eight data points you want to explore into the final eight rows of your data range and Bob’s you Uncle. This would work for any number of data points where you don’t have enough data for Excel to create the number of pip elements you want.

I have to admit that for the main pip chart, the pie on the left, adding dummy data looks a bit iffy as it adds markers for 0%, but to overcome this problem, don’t enter anything in your dummy data point values … before and after, look carefully:

Before: dummy values entered as 0 |
After: dummy values left empty |

For good measure, you might like this clean version too:

Download the Excel file pie_pie

Duncan Williamson