For most of us, our first experience of sports is on the school playing field..this assumes you are lucky enough to have one. But finding out the number of schools with playing fields in England is not that easy as evidenced by the government’s recent revisions of the number of sold/on sale playing fields.
After all, someone has to count school playing fields…. and maybe counting them is more of a challenge than we might think: what do we mean by ‘school playing field’? which type of school? geographical coverage? period? etc.
In light of this, it was good to know that we were not alone in suspecting that recent claims that an estimated 10,000 school playing fields were sold off between 1979 and 1997 needed to be challenged. Where had this strangely high (and nicely-rounded) number come from? BBC Radio Four’s ‘More or Less’ team found that the figure was less of an estimate and more of a guesstimate or ’ball park’ figure. A check of Hansard found that until 2007 opposition MPs had been citing 5,000 – and not 10,000 – as the level of playing fields sold by previous governments. Why had this statistic suddenly doubled? And where had the 5,0000 and 10,000 figures come from?
Well..the 10,000 figure had been taken from a 2008 Dept for Culture, Media and Sport report. Yet delving deeper into the figure’s provenance, the paper trail soon went cold.
The source of the 5,000 playing fields figure was dubious too……a Lords debate in 2001 revealed it to to be a “guesstimate” and not a reliable count. ’More or Less’ researchers found that the ’method’ used to guesstimate the 5,000 playing fields was pretty much a case of how not arrive at an estimate. It began with a 1983 snapshot survey* to which snapshot figures for grant-maintained schools were added (in this case, they added 64 fields across a particular 30-month period in the mid 1990s.) Then came the assumptions. It was then assumed that all schools were sold off at the same rate as grant-maintained schools (unlikely as grant-maintained schools are more free than most to use their budgets as they wish) and it was further assumed that between 1979 and 1997, playing fields were sold at the same rate as during this chosen 30-month period. As a precaution (!), the figure was halved and then rounded to 5,000.
Either way, this figure has stuck. It’s what More or Less’s Tim Harford calls a ‘zombie statistic’ that just keeps coming back at you….even a parliamentary question failed to exterminate it.
In defence of guesstimates, they can offer a useful first step on a path towards a more thorough count as more accurate information is found. Sometimes guesstimates ignore better information. Sometimes they reflect the absence of better information. In this case, “no one really knows the true figure because nobody counted“. ‘More or Less’ researchers found that playing field sales have only been counted since 1998 (and we still have no idea how many there were then or how many there are now).
They suggest that as governments say that they have mainly sold playing fields when schools have been sold, a better way of estimating school playing field numbers might involve looking at school closures…apparently 3,000 schools closed in England between 1979 and 1997, many in response to changes in the birth rate and so somewhere in here are some of the school playing fields lost during this period.
Suddenly, everything seems a lot less certain and begs the question ‘was a guesstimate of this kind the right figure to take centre stage in parliamentary debate?’.
* not a survey of fields sold but of fields under threat (and, in fact, not just school fields)