League tables are the first thing most parents look at and the thing they most often misread. They are genuinely useful — but only if you know what each measure is actually measuring, and most of the common ones are measuring intake at least as much as teaching.
The two kinds of measure
Everything in a school performance table falls into one of two categories, and confusing them is the root of most bad decisions.
Attainment measures tell you how well pupils did in absolute terms. The percentage achieving grades 9-7 at GCSE, the percentage achieving A*-B at A-level, the average points score. These are heavily determined by who the school admitted. A school that selects the top 10% of the ability range will post excellent attainment even if its teaching is mediocre.
Progress measures attempt to compare a pupil's outcome with what pupils of similar prior attainment achieved nationally. Progress 8 is the main one at GCSE in state schools. These get much closer to what a school adds — though they have their own well-documented flaws.
The single most useful habit: whenever you see a headline percentage, ask who was in the cohort? A selective grammar school and a comprehensive with an all-ability intake cannot be compared on attainment. It is not a fair fight and it was never meant to be one.
What the main measures mean
Progress 8. A score around 0 means pupils did about as well as similar pupils nationally. Positive is above, negative is below. Roughly, +0.5 is strong and -0.5 is a concern. It applies to state schools; most independent schools do not report it, which is one reason cross-sector comparison is difficult.
Grades 9-7 at GCSE. The old A*/A equivalent. A useful indicator of high-end performance, but a school with a strong 9-7 figure may still be poor at supporting the middle of its cohort.
Grade 5+ in English and maths. The "standard pass" benchmark. More informative than the 9-7 figure for a broad-intake school, because it tells you how the middle is doing.
A-B and A-A at A-level.** The main independent-sector comparators. Watch cohort size: a small sixth form produces volatile percentages, and a single strong or weak year distorts everything.
Average points score. Less headline-friendly, but more stable than threshold measures because it reflects the whole cohort rather than the pupils sitting near a boundary.
Our article on how to read school exam results goes into the individual metrics in more depth.
Where the numbers can mislead
Small cohorts. With thirty pupils, one leaving or joining moves a percentage by more than three points. Single-year figures for small sixth forms should be treated as noise. Look at three years.
Subject entry patterns. A school can lift its A-level profile by steering pupils away from subjects where grades come harder, or by declining to enter borderline candidates. Ask how many started the course versus how many were entered.
Cohort filtering. In the independent sector, some schools do not carry all pupils through from GCSE into their own sixth form. That improves A-level figures without improving teaching.
Curriculum mix. Schools offering the IB or a mix of qualifications appear inconsistently, or not at all, in A-level tables.
Selective entry at 16. A school admitting external sixth formers on high GCSE thresholds will post better A-level results than its own Year 11 profile would predict.
A single strong year. Reversion to the mean is real. A school that jumped twenty places last year will probably drop back.
What league tables cannot tell you
This is the more important list, because these are the things that determine whether your child is happy.
- Whether the pastoral care is any good. No table measures this, and it matters more than any percentage for most children. See pastoral care and finding a supportive school.
- What happens to a child who struggles. Tables show outcomes for those who did well. They are silent on the bottom quartile.
- Staff turnover and morale. Not published anywhere. Ask.
- Whether your child will be happy there. The one that actually decides how the next seven years go.
- The strength of the specific department you care about. School-level averages hide enormous subject variation.
- How the school treats children who are not academic high-flyers.
Using tables well
A reasonable method:
- Use tables to build a longlist, not to pick a winner. They are a filter, not a verdict.
- Compare like with like. Selective against selective, all-ability against all-ability.
- Look at three years, not one.
- Prefer progress measures where they exist.
- Then go and visit. Everything that matters after the longlist stage is visible on a school visit and invisible in a table. Our guide to making the most of an open day covers what to look for.
- Ask the school about its own numbers. A head who can explain a dip candidly is a better sign than one with a flawless record and no explanation for anything.
Where to find the data
For state schools, the official source is the Department for Education's Compare School and College Performance service, which publishes attainment and progress data directly. Inspection reports are on Ofsted's reports site and, for most independent schools, the Independent Schools Inspectorate.
On this site you can see schools ranked by A-level results and GCSE results, along with tables for private schools, grammar schools and boarding schools. Our tables are built from published results data, and the same caveat applies to ours as to everyone else's: they rank on attainment, so a highly selective school will rank above a school that may be adding more to its pupils.
The honest summary
League tables answer one question well — how did the pupils at this school perform in public examinations — and they answer it in a way that is heavily shaped by which pupils the school admitted in the first place.
They are worth twenty minutes at the start of a search and very little after that. The decision gets made on the visit.
Next step: browse the school league tables to build a longlist, then compare your shortlist properly on the comparison tool.