Do the tables really do add up?
BBC Radio 4's More or Less was broadcast on Thursday, 22 January, 2004 at 1500 GMT.
This week, "value added" league tables for schools.
We've seen the figures, we've heard the arguments, but what have we actually measured?
More or Less gets to the bottom (and top) of the tables.
We look at comparisons of grammar and comprehensive schools and ask both about the accuracy of the measurements and the conclusions drawn from them by politicians.
Producer: Michael Blastland
Editor: Nicola Meyrick