The so-called ‘data’ gathered from schools is hopelessly unreliable, because teacher assessment is inevitably biased, and even external assessments can never reliably assess learning, only performance on a given day.
This hopelessly unreliable data is then subjected to invalid methods of statistical analysis. Despite the fact that schools are not representative samples of the population, they are treated as if they were, and their targets are set and results judged accordingly.
So we start with unreliable data, then we push it through invalid analytical procedures, and the end result is lots of spreadsheets coloured in beautifully, which can be used by bureaucrats and school leaders to make their decisions.
When they gaze at these beautiful spreadsheets, managers and inspectors are little better than King Saul or Macbeth, off to consult the witches to find out how things will go.
People have always wanted to know more than they possibly can know, especially about what the future holds. Because their desire to know is so strong, they are in great danger of deluding themselves into thinking that they really do know. Gamblers are a case in point. If the roulette wheel came up black three times in a row, then they decide it will certainly come up red next time. They may even apply the principles of probability to their decisions to place a bet, forgetting that probability can never predict the future. Each spin of the wheel is unique and not influenced by previous events.
We know how addictive gambling is, and the sensation of power and control conferred by the beautiful spreadsheets is equally so. It is a kind of forbidden fruit, or, better, it is like the Turkish Delight offered to Edmund by the White Witch. It is a delightful confection which, once tasted, will be almost impossible to resist.
Gamblers pay for their hubris with their own financial ruin. But when school leaders and inspectors allow themselves to be deluded in similar ways, it is the lives of pupils that are ruined, and the careers of classroom teachers.
We need a few more Davids to stand up to the deluded arrogance of the Sauls. The sharp pebble in your sling will be the truth.
Further reading: Jack Marwood’s eloquent and devastating appendix to David Didau’s Wrong Book is a good place to start.