Charts and graphs that make your reporting stand out Part 1: The Chord Chart

Everyone who views or develops reports on a regular basis will be familiar with the standard forms of graphs and charts used in almost every report or dashboard. Bar charts, line graphs, pie charts and bubble charts are a stable of modern reporting, each of which have built in templates within standard reporting tools such as Excel, Business Objects and tableau.

In this series of posts I want to highlight the vast range of charts that have been overlooked by analysts, designers and software developers. These charts provide visualisation of datasets in a distinctive manner and provide a way to display data in a meaning full way.

The Chord Chart

The chord chart is an excellent way to visualise the inter-relationships between entities in a dataset. In my opinion it is one of the most underutilised forms of reporting and makes connections within data very easy to see at a glance.

The connections between entities displays that they share something in common. This makes Chord Diagrams ideal for comparing the similarities within a dataset or between different groups of data.

Nodes are arranged around a circle, with the relationships between points connected to each other either through the use of arcs or Bézier curves. Values are assigned to each connection, which is represented proportionally by the size of each arc. Colour can be used to group the data into different categories, which aids in making comparisons and distinguishing groups.

The chord chart can be setup in 2 distincive ways, firstly it can show the relationships between a fixed set of entities and how each are connected by the flow of data. For example the chart below shows the movement of staff from a number of tech companies.

From this visualisation it can be easily seen that a large number of staff move from Microsoft and Yahoo to the others companies. It also shows that Facebook have no employees moving to it's rivals.

In a dynamic reporting setting the data displayed can be selected to to show a single part or parts of the chart. i.e. only the employees leaving Apple.

The second variation of the chart allows more than one set of entities to reside within the circumference of the circle. The example below shows you how each sales person contributed to the quarter sales results

Again from a quick glance it can be seen that a couple of sales people had an exceptional second quarter and that a number of them performed poorly in relation to the others overall.

In conculsion the chord chart is a versitile and provocative tool that can be used to display data that other forms of visulisation fail to represent.

Over the course of the next few weeks I will be presenting a number of other chart types and hopefully converting some of you to the benefits of using different reporting visulisations.