Sanity check

I'd normally post content about data and graphs over at www.badgraph.co.uk - but to be honest this one needs particular attention.
I've blogged before about who the audience is on a school web site (parents, prospective parents and learners foremost) is and what they want from data (to be able to make a decision about the school) - anything else is either ego or the data is best available as a download, not front and centre.
I've hidden the school, but I almost didn't:

I challenge anyone, without prior preparation to actually understand this chart. I wonder if even the school does.
Concerns:
Title: "Rolling three year average statistical process control chart"
Statistical Process Control Charts (SPCC) are used in industry to tabulate the output of a machine / process - reducing a school to a "result factory" shows a worrying lack of empathy over the role of the school and the development of young people. (The chart might be useful, but the title isn't)
The chart itself plots "Average Standardised Residuals" - eh? Any idea what they are (without waxing lyrical)? As an educator do you know? Would a parent? Firstly, what's a residual and then what's a standardised one?
Dark grey = 2 standard deviations, Light grey = 3 standard deviations << written in words! Firstly - what about a proper legend and secondly what does that mean? Is it good or bad?
The school data itself
Now, as I can't read this chart, and I have no idea what it's showing. What does the school data mean to me? Well I can tell it's higher than the rest - so that must be good? Right? But wait, the school's line goes down from 2011 to 2014 - is that bad / good - does it show improvement or is the place going to the dogs?

Googling "average standardised residual" - you'll find some links to www.cem.org and some information on these charts - and yes, they might be useful - but without training I'm not sure if this is demonstrates an ego chart or a fundamental lack of understanding over what normal people want from data visualisation.

Call to Action
  • Please, please show your charts to a select group who will tell you if it makes any sense to "Joe / Jane Public"

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