Hundreds of small primary schools had their Sats results published in national league tables for the first time this week as the amount of data released by the Government doubled compared to last year.
Until now, around 1,000 small schools were exempt from the tables because they had fewer than 10 children taking the tests. This year, the limit was dropped to just five pupils, fuelling fears that the performance of just one child could have a big impact on a school's ranking.
The move to publish the data is part of a wider Government drive to make available as much information on school performance and wider public services as possible.
The National Association for Small Schools (NASS) has also raised concerns that dropping the numbers will mean individual children's results will be identifiable. Mervyn Benford, information officer at NASS, said that the Department for Education's zeal for making data available made it a "serious risk" that people would be able to work out the results of individual children who attend small village schools.
"Everybody in the village will know the two bright level 5s and the ones who didn't get level 4," he said. "The exemption was set up to protect children from identification.
"If we are going to identify one child in a small school, then why not every child (in all schools)?"
Russell Hobby, general secretary of heads' union the NAHT, also raised concerns, pointing to the impact one child's results could now have on the league table position of dozens of schools. "Publishing small numbers ... is not very helpful because the statistics become meaningless," he said. "One child can throw the statistics massively in one direction or the other.
"I have no problem with more data being available. But when you go into finer and finer detail, it becomes both meaningless and potentially harmful."
This year's league tables also publish the number of children in individual schools achieving level 4 results in English and maths who are in care or eligible for free school meals. In addition, they show how many pupils were performing above and below the expected level for their age when they started Year 6, to make it easier to gauge how much progress they have made. The number of pupils with special educational needs statements are also included in the tables, even when this only refers to one pupil.
The DfE has said that the extra information is part of a commitment to greater transparency, which will enable parents and the public to hold schools to account. But despite 123 pieces of data now being available for each of the 16,000 primaries in England, there are still only two headline measures: the percentage of children achieving level 4 in both English and maths and the percentage of children making expected progress between the ages of seven and 11.
These measures together determine whether a school is seen as a success or a failure. Those that fail to meet them could be closed and reopened as academies or merged with a successful local school. The weakest 200 are already due to be converted into academies next September.
A spokeswoman for teaching union ATL said parents did not want an abundance of extra information. "What is important is finding a school at which their child will thrive and we find burdening them with huge amounts of information will confuse a lot of parents," she said.
The Bew Review of key stage 2 testing has proposed more changes for the league tables. Some, such as publishing separate reading and writing scores, will come in this year, while others, such as three-year rolling averages, will be introduced in 2012.
Information included in the primary school league tables for the first time this year:
Results of small schools where between six and 10 pupils sat the tests.
The percentage of pupils eligible for free school meals attaining level 4 in English and maths.
The percentage of children in care attaining level 4 in English and maths.
The proportion of pupils who were already above and below the expected level at the beginning of Year 6.