The publication of school league tables based on exam results is one of the most contentious issues in education.

Critics argue tables are misleading because they focus on one measure and do not inform parents about the wider context of a school or how much it helps pupils improve.

When tables are published they are often used by families as a shorthand for whether a school is “good” or not when that is not necessarily what they tell us.

However, there are strong counter-voices, with the UK Statistics Agency criticising the Scottish Government in recent years for its strategy of publishing school results individually without making comparisons.

Read more: The top 50 state schools in Scotland 2019

In fact, the government and schools quango Education Scotland works hard to try to prevent easy comparisons on exam results, publishing data on a school by school basis and not in an overall table.

That means parents wishing to make a comparison between two or more schools have to view information for each school separately, even if those schools are in the same local authority area.

Our tables allow for direct comparison, but there are a number of important caveats.

Read more: How every secondary school in Scotland ranks

Our benchmark of the proportion of school-leavers achieving five or more Highers appears a good one to judge performance. However, it does not tell us whether those results were achieved in fifth or sixth year, so favours schools where more pupils stay on.

The measure also takes no account of how many pupils are in a year group meaning small schools can yo-yo up and down based on the results of a handful of pupils.

The major issue with tables, which is almost impossible to address, is that they don’t take any account of the social mix of a school. Because deprivation has such a significant impact on exam performance, tables tend to make schools in middle-class areas look better than those serving more diverse or disadvantaged communities.

Read more: Poor pupils improve exam results, but gap with the richest widens

This is not necessarily anything to do with the quality of the school, but simply because schools in leafy suburbs have a higher proportion of pupils from richer backgrounds who tend to perform better in exams.

It should also be remembered that the figures are not worked out as a proportion of those who sat Highers, but as a percentage of the overall S4 roll, meaning the figures are not a “pass rate” at Higher.

To give greater context to the data, we publish the Scottish Government’s “virtual comparator” benchmark showing how a school should be performing.

We also publish the proportion of pupils from the poorest neighbourhoods to give further context.