Introducing Sankey

Since the trend, and the underlying reasons for it, have remained the same for the last two or three years, I decided I would do something more interesting with this post than just give you chapter and verse on the headline developments in more detail.

Instead, I want to introduce you to a fabulous resource from the Ministry of Justice: their interactive  Sankey diagram which lets you see how groups of people’s offending history is reflected in how the courts sentence them.

In case you don’t know (and I certainly didn’t) Sankey diagrams display flows and their quantities in proportion to one another. The width of the arrows or lines are used to show their magnitudes, so the bigger the arrow, the larger the quantity of flow. Flow arrows or lines can combine together or split through their paths on each stage of a process.

The MoJ Sankey diagram allows you to focus on a particular group of offenders by age or gender and/or a particular type of offence and lets you see instantly how the criminal justice system sentences them. 

You can all see differences in sentencing on a yearly basis going back to 2007.

The diagram is delightfully intuitive and engaging and I spent a happy half hour trying out all the permutations. 

It’s important to remember the limits of what the diagram can tell you. For instance a larger proportion of women than men receive a suspended sentence for sexual offences (while immediate custody rates are similar) and while a very small proportion of men are dealt with by an absolute discharge, no women receive this court disposal. However, the profile of sexual offending by men and women is different, so you are not necessarily comparing like with like.

Nevertheless, there’s much to be learned by this interactive approach and you can see why some say:

A Sankey diagram is worth a 100 pie charts.

I hope you find the examples I’ve chosen interesting and, more importantly, you will go and try out the resource yourself.