After my recent postings, I was sent this from a colleague - and actually it's not a bad stab at representing the data - just the execution and lack of Excel-fu lets it down:
In essence, it's a panel chart - but drawn as a bar chart, comprised of 10 series - which Excel has obligingly colour coded. But to be honest, all I can see is that (as you would expect) you get more learners getting the grades as you go from A* to A to B etc.
Not sure what parents are supposed to extract from this.
The same data can be easily represented as:
At least with a proper panel chart I can see the underlying trends for the grades - which for the A*-A seems to be quite an increase from 2003 to 2013 - however, what I can now also see is that the A*-B and A*-C seem to decline slightly over the past 5 years.
I'm not sure what value a parent (or anyone else for that matter) would get from this visualisation - the chart would appear to show an improving situation over time - with more and more learners "passing" with A*-C grades.
But what about the grades themselves?
Taking the A* results from the A*-A, and the A*-A from the A*-B etc will give us the actual numbers achieving each grade:
The same data, but a different picture.
Here I can see that the all grades A, B and C have (over the past 5-7 years) seen a year on year decline - what looks like a different picture.
I'm not sure which view is more useful - but I suspect that this is a case of "don't use a chart"
From 2003 - 2012, the average A*-C is 97%
...would appear to be a stronger message than the charts themselves - and if a chart is desired, add the averages:
Call to action
- Don't overload colours - not only does it look poor, it actually makes things harder to understand
- Learn Excel charting functions, such as panel charts
- Don't use a chart when text will do
- Annotate charts with averages to make the interpretation easier