Detailed Documentation

About SDA's National Single Indicator


In 1993 we delivered the first school performance tables on behalf of the Department for Education. We’ve powered them ever since. They are a comprehensive source of information, but we think they have become complex.

Our mission is simple: to cut through the noise and get to the point.

Our National Single Indicator combines a number of standardised and well documented measures of school performance to provide a simple, straightforward benchmark of how well a school is doing. While the NSI is our own device, it is firmly based on the Department of Education’s own data and is derived from the following four key measures:

  • Pupils making (or exceeding) the expected progress in English and Mathematics
  • Pupils achieving the main threshold level
    • For Key Stage 2: Percentage of pupils achieving Level 4 or above in Reading, Writing and Mathematics
    • For Key Stage 4: Percentage of pupils achieving 5+ A*-C GCSEs (or equivalents) including A*-C in both English and Mathematics GCSEs
  • Pupils’ Average Point Score
  • The main Value-Added measure
    • For Key Stage 2: Reading, Writing and Mathematics value added (KS1-KS2 VA measure)
    • For Key Stage 4: Value Added measure based on the best 8 GCSE and equivalent results

In our approach, we take an amalgam of all of this information and turn it into something people can use to compare schools and make choices. By itself, it gives a good indication of how a school is performing relative to the national picture in terms of its attainment, its progress and its ability to stretch out beyond its environment. Together with a number of other factors that we publish, it provides a forthright means of gauging how well a school is doing, both of itself and compared to others.

Learn more about these variables and how our NSI is calculated.