Progress 8 - a data mangling bunch of arse?

[noblegiraffe]

I found this dissection of the progress 8 calculation very interesting:

headguruteacher.com/2015/05/02/progress-8-looks-like-data-garbage-to-me/

I can see exactly the problems that he mentions coming up on MN in the future. "Oh, this school got 0.2 so isn't as good as the one that got 0.3" completely ignoring the error bars which render the comparison nonsense.

"Progress 8 is not a measure of school effectiveness." A quote from the people who came up with it. I can see that needing to be highlighted in the future. If you don't make it to the bottom of the original analysis, the blog here explains why:

www.educationdatalab.org.uk/Blog/May-2015/Why-do-pupils-at-schools-with-the-most-able-intake.aspx#.VU3LTNpVhBd

Interesting stuff Noble, and mostly above my head. I am not a teacher but as a school governor I went to a training session laid on for GB. (My DC are no longer at the school).
Who on earth came up with that lot?
One thing that stood out to me was the fact that high achievers on entry really struggle to score well. An example was given of pupil A with high SAT scores who was predicted A/A* at GCSE and barely registered. Whereas child B who came in with level 3s and was predicted two or three modest GCSEs scored very highly under progress 8.