How can a school have more than 100% of pupils staying on beyond 16?
Results can be misleading, says the head of Brae High School
BBC News website education editor, Gary Eason, looks at an example of how information published about schools in Scotland can be hard for parents to understand.
Shetland Islands Council has only two senior high schools: Brae High and Anderson High.
On the face of it, Anderson gets much better Highers results.
But then it also has a rather better staying-on rate: remarkably, it is usually well over 100%.
In fact what happens is that Anderson takes in a significant number of pupils from Shetland's junior high schools, which have no fifth or sixth forms.
They swell its numbers and inflate its exam results.
The Standard Grade results for the schools' fourth year pupils in 2003 show that 90% of those in Anderson attained five or more general grades. In Brae it was 86% - very similar.
But consider the performance of the same pupils in the following year.
At Brae, 46% attained at least one Higher. In Anderson it was exactly double that: 92%.
Or at least, that is what the education department says - because it relates the results back to the numbers who were in S4 and does not take account of the influx from other schools.
The truth is rather different.
We obtained from Seed a different set of results: the percentages of those in S5 who obtained one or more Higher.
In Anderson it was 73%. In Brae it was 79%.
"The raw results are very misleading," said Brae High's principal, Robert Grant.
He said he had asked the education department to change the way it did things.
He stressed that results were only one part of "the big picture" about a school.
They could be useful, but particularly if there were small numbers of pupils they could be "significantly misleading".
"Publishing them in the way they are published - they can maybe do more harm than good, to be quite honest."
His school, with only about 30 pupils in each year group, was highly affected by family mobility.
"Say a couple of kids move away - it can skew everything."
He said that, to be fair to the official statisticians, there was a constant dialogue and they did try to improve their presentation of the results.
For now, he had "a wee bit more faith in parents" to make "sensible decisions".