KenR wrote:

Actually that not correct - you can work it out based on the previous years average standardisation scores (shown under the scores in the sticky) - assuming only small changes in the number of candidates taking the exam

I did the calculation for KE-Ways as an example

For last year - the KE-Ways last candidate score was 227 with an average Std score of 114

114 is the 82nd percentile - so the top 18% candidates were successful out of 100%

This is equivalent to a probability of 1:5.55555

Increasing the year-7 entry from 150 to 180 will have an inverse effect on the success ratio in proportion to the increase.

This will have the effect of increasing the probability of success to 1:4.629629

Which is the equivalent of the 78.4 percentile

In terms of standardisation tables, 113 is the 80th percentile and 112 the 78th percentile. But closer to 112 in this case.

So assuming:-

(a) the cohort numbers remain unchanged from last year, and

(b) the distribution profile of choices by parents is similar to last year (both big assumptions)

We would predict the KE 5-Ways pass mark for the last successful candidate to drop from 227 to 224 if they increase the PAN from 150 to 180

Hope this helps

(The mathematical or statistically minded amount you can work this out for the other schools I hope)

Hmmmm what's that I can smell? Its the sweet smell of statistics in the morning!!

I was thinking that somehow we need to factor in the culmative effect of more places further up the grammar school food chain on the less competitive ones. So if KEH has an extra x places but it will also benefit from pupils who would of taken up those places going to KECHG. Can we assume that KEH would therefore effectively benefit from 2x increased places?