A TEACHING union has claimed parents will continue to have "misleading and sporadic information" unless there are fundamental changes to the Welsh school banding system.

Ahead of the publication of school banding results next month, in which secondary schools across Wales will be categorised from one (good) to five (bad), the National Union of Teachers (NUT) Cymru has called on the Welsh Government to examine how often the bandings are published as well as the system by which they are ranked.

Commenting on next month’s school bandings, NUT secretary David Evans, said: "At present, the annual school bandings are very sporadic due to the nature of making a snap judgment on just one cohort of students.

"That has resulted in some very volatile results where schools at the very top of band 1 one year have dropped to band 4 the next; or schools that have received sector leading Estyn inspections have dropped from band 1 to 3 in the same year.

"That really does not inspire confidence in the system for parents and calls into question the validity of the results."

He said the system - which was developed by former director of education in Newport and now director of school standards at the department for education in Welsh Government, Dr Brett Pugh - does not allow for bands 4 or 5 to be empty, and despite improvements in school performance, there are still roughly the same number of schools in bands 4 and 5.

"It does not really give parents a clear picture on how schools in Wales are developing," he claimed.

A Welsh Government spokesman said the administration is content with the way banding data is calculated and the frequency with which it is published.

"It’s important to remember banding is not a measure of national improvement – it has to be seen against all the other performance information that we have on how we are performing against our key national priorities," he said.

"We will see progress through looking at how these measures are improving year on year, at national, consortia, local authority and school level."

On Tuesday the international PISA results for 2012, which compare OECD countries including Wales against one another for numeracy and literacy, will be published.