---
title: "Part-to-whole: Comparisons and compositions"
description: Visualisations allow you to ask questions of your data, and the type of question you want to ask will determine the chart type. A ton of questions you might ask...
---

[DDBM Blog ](https://www.ddbm.com/blog)

# [Part-to-whole: Comparisons and compositions](https://www.ddbm.com/blog/2021/09/20/part-to-whole-comparisons-and-compositions)

 Geschreven door [Thijs Trompenaars](https://www.ddbm.com/blog/author/thijs-trompenaars) | 19 Sep, 2021

Visualisations allow you to ask questions of your data, and the type of question you want to ask will determine the [chart type](https://www.theinformationlab.nl/en/2021/08/31/how-to-choose-the-right-chart-type/). A ton of questions you might ask about your data will hinge on a **comparison **between values. Which region was responsible for most sales? What product generated most profit? These questions are answered quickly by gathering and comparing different values in your data. 

## Visualizing comparisons 

Let’s look at some data from my local library. Here’s a little table showing the number of books by genre and section. 

I can already make some quick comparisons without doing too much math. For instance, the biggest genre appears to be Romance novels, and the non-Fiction section on the whole seems to be smaller than the Fiction section. Of course, there’s an even faster way to spot these trends: Visualisations! There are many ways to show a comparison; I prefer the humble bar chart: 

Notice that the questions I asked needed *absolute *numbers. In my charts, I can clearly see values by category, sort and filter as I please, make comparisons, and answer my questions.

Suppose now I want to ask what genre contributes most to each section, or track the relative growth of each section over time. These questions also involve comparisons, but they are subtly different. I am not comparing different values *per se*, but comparing the relative contribution of those values to a bigger whole. In other words, I am interested in a **composition**, or part-to-whole relationship.  

## Comparing compositions 

With compositions, I don’t really care so much about how values compare to other values. Instead, I want to know how the individual parts make up the whole. I could try to answer these questions by looking at my bar charts above, but there are many chart types devoted to compositions that do a much better job. These part-to-whole chart types immediately focus our visual attention on the *relative *importance of every part to the total value in the data.

In upcoming posts, I will explore some of these chart types, when they are best used, and how to build your own using Tableau. 

Continue to Part 2 [here](https://www.theinformationlab.nl/en/2021/09/21/part-to-whole-visualising-compositions/).

[Volledig bericht weergeven](https://www.ddbm.com/blog/2021/09/20/part-to-whole-comparisons-and-compositions)

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