Traditionally secondary schools are rated primarily by exam results, but I've crunched some numbers to attempt to find a better way of rating how good a school is, and found some surprises. Read on and I'll explain why, present the results, and then I'd be interested if your experiences match them or not.
There are problems with an over-reliance on exam results. Success in exams correlates extremely highly with wealth - while there are many exceptions at individual levels, on the whole children from wealthier families receive more support at home, via tuition etc., and do better at school. Schools with a wealthier catchment will therefore do better for the same quality of teaching, good teaching may be masked by poverty in a poorer catchment, and bad teaching could theoretically be hidden by a wealthy catchment.
Firstly, I've taken a weighted measure of exam results and adjusted it for poverty, as measured by the number of people qualifying for free school meals (broadly speaking household income £16k or less). Secondly I've looked at all the inspection reports on teaching quality and simply grouped schools by similar results there. I'll post the results in replies to this message.
On numerical method: exam results are weighted 2x "five or more A-C highers %" + 1.5x "three or four A-C highers %" + 1x "one or two A-C highers %". That sum is then divided by the percentage of students NOT receiving free school meals, e.g. if 20% take school meals, the weighted exam result total would by divided by 0.8. There are doubtless many other ways of doing this but a similar result is likely. Results to follow.