Melanie Butler shows how you can check the consistency of school groups by using benchmarks based on the range of results
LARGE GROUPS: The consistency benchmark is The English Network (TEN), which is not a chain or franchise group but an association of independently owned schools. Its consistency is shown by the fact that all ten of the member schools fit within a range of eight points, which is a normal distribution range.
All score between 8 and 15 points, putting them in the top 20 per cent of language centres in the country, based on British Council inspections, and their median score is 13.
Kaplan has a profile closest to the benchmark, with all ten of its schools in an eight-point range, a median score of 8.5 and half in the top 20 per cent, making them consistently good to excellent. EF, nearly half of whose schools are five-star, has a wider spread of results. Both EC and Embassy have consistency of range but a lower median score.
SMALL GROUPS: The Eurocentres chain is the benchmark for groups of five schools or fewer. Its astonishing consistency, four schools with a 13-point score and one just three points lower, is in part due to the fact that all the schools were inspected in the same year following a major standardisation project.
To achieve consistency, a small group of schools should all score within four points, or one standard deviation. Language Studies International (LSI) is the closest to this benchmark and, with two of its four schools due for re-inspection this year (as shown by the circles), it may improve its median average score. St Giles currently has the highest median score, generally a good measure of consistency, and with the outlier from its other high-scoring schools due for re-inspection its consistency range should improve.