Teacher shortages: are a handful of schools a big part of the problem?

Sam Sims and Rebecca Allen. 
 We recently met a Newly Qualified Teacher (NQT), let’s call her Ellen, who had been delighted to get their first teaching job in a North London primary school deemed outstanding by Ofsted. She arrived on the first day of term looking forward to the challenge of teaching, but by lunchtime it dawned on her that the school had lost 100% of its classroom teaching staff since the previous academic year. At the time, she wondered what could have happened to make all these teachers leave.
She soon found out however, as she spent the next year being pressured into an unsustainable workload and subjected to highly bureaucratic and, at times, callous management. At the end of the year, all the classroom teaching staff left the school. Many of them, including Ellen, left the state education sector altogether.
We wanted to know whether this was an isolated anecdote or a more widespread
problem. So in our paper for the February issue of the National Institute Economic Review we use the School Workforce Census to quantify the number of schools that recruit an unusually high proportion of NQTs and see an unusually high proportion of such teachers leave the profession within a year.
Identifying such schools is, however, challenging. For example, a small primary school might only recruit one teacher every few years. If this happens to be an NQT, and that teacher decides to leave through no fault of the school, then this school would show up as recruiting 100% NQTs and losing 100% of them. This is clearly not the same kind of phenomenon as a school losing 100% of their classroom teachers two years in a row. We needed a way to distinguish the two.
In order to avoid treating small schools overly harshly, we used a technique from the medical statistics literature called funnel plots, which were introduced by David Spiegelhalter, currently President of the Royal Statistical Society. The two funnel plots below show the proportion of teachers recruited by each school in the North West of England across the last five years that were Newly Qualified (left hand side) and the proportion of these that left within a year (right hand side). The horizontal line shows the regional average and the curved lines show the “control limits” beyond which we argue that schools are displaying unusually high turnover – note that these limits are wider for smaller schools. For full details of our method and the rationale for funnel plots, see our paper here.

Our analysis identified 122 schools in England that both use and lose an unusually high proportion of NQTs from the profession. These schools have an NQT wastage rate three times the national average and between them lost 577 NQTs from the profession between 2010 and 2014. We show that if these schools had attrition rates equivalent to the average school then 376 additional teachers would have progressed beyond their NQT year. For context, this is equivalent to 22 per cent of the nationwide shortfall of teachers in 2015.
So it seems that Ellen was indeed unlucky: very-high-turnover schools are rare. Unfortunately, they are still common enough to be making a material contribution to the system-wide teacher shortage. What can be done about this? Funnel plots are a simple, reliable and low-cost way of identifying these schools. This would allow them to be provided with additional support to improve their retention of teachers. Alternatively, we might consider providing this information to trainee teachers to allow them to make a more informed choice about where to accept their first teaching job. If Ellen had enjoyed access to that information, she might still be in the classroom now.