It's too early to say with certainty how free schools are performing

The Department of Education yesterday announced the approval of a further 38 free schools. Now totaling 331 open or approved free schools, the Department has said these schools are twice as likely to be 'outstanding' under the new Ofsted framework.

We're waiting for the Department to send us the details on this claim, but the data we've seen suggests it's too early to say for sure how well free schools are doing compared to other schools.

We've previously looked at similar analysis by the New Schools Network. It was based on the first 24 free schools that opened in September 2011 - a small number from which to be able to draw conclusions.

Ofsted's management information shows 42 free schools have now been inspected. The majority still haven't. Even if the Department is comparing the latest results, there still aren't many.

The free schools that have been inspected may also be atypical in their composition. Ofsted told us previously that many newly-opened schools fill their places gradually, so a secondary free school which opened in September 2013 may only have Year 7 pupils now, Year 7 and 8 pupils in September 2014, and so on.

Taking account of these caveats, it's going to take time for the full picture to emerge.