A rich mix of different explanations have come under scrutiny this week as the education world looks to explain the drop in the number of KS2 pupils winning the top level 5 mark in this year's Sats.
Most dramatically, the percentage of 11-year-olds achieving the highest mark in English fell from 34 per cent to 29 per cent, a situation schools minister Jim Knight said needed "a bit more examining".
"We need to principally examine the interplay between reading and writing tests," he said. One possible explanation for the drop in results was the long writing task - a fictional biography of fairground ride inventor Pip Davenport. It has been criticised as being difficult to achieve top marks.
One marker, who chose to remain anonymous, said: "I found they struggled because they scored more marks if they kept to the prompts, which were quite protracted. A child who got into writing a story rather than a biography lost marks, they would shoot off with a story, but hadn't remembered to have him get married."
To reach level 5, pupils needed to compose complex sentences, using subordinate clauses and stylistic features, such as "Pip's last words were `Never let reality get in the way of your dreams'."
Another possible factor that might take the blame for the drop in the awarding of level 5 is that teachers focus on pupils at level 4 because they are the results by which schools are measured.
This has previously been recognised as a problem. The Government did try to counter this by setting a target in 2002 of 35 per cent of pupils reaching level 5 by 2004. But when this wasn't reached it was quietly dropped, and the idea has not been mooted since.
One of the most popular explanations for the fall has been widely reported as the demise of "borderlining", the practice of checking pupils just below a level threshold.
This was dropped for the first time this year for reasons of accuracy. Government statisticians say this can account for a decrease of up to 2.9 percentage points in those pupils winning the top mark.
Finally, of course, there is the chaos surrounding the marking process. Six per cent of pupils' English marks were missing from the statistics released this week - compared to less than 0.5 per cent last year. Of those which have been marked, appeals are still pending. These have been taken out of the hands of contractor ETS to be dealt with directly by the National Assessment Agency. Such checks could change the marks by one percentage point either way.
Tuesday's provisional figures did, however, show a one percentage point rise in pupils achieving level 4, the expected level in English, from 80 per cent to 81 per cent. Maths enjoyed the same rise, from 77 per cent to 78 per cent. Science has stayed static at 88 per cent.
Combined statistics show 61 per cent of pupils reached level 4 in reading, writing and mathematics, which meant that 220,000 pupils missed out on a level 4 in at least one of these subjects.