THE KEY STAGE 1 (KS1) TO KEY STAGE 2 (KS2) VALUE ADDED MEASURE

What do we mean by value added?

Some pupils will find it particularly difficult to reach the level expected for their age in assessment tests. It may be, for example, that they have significant special educational needs (SEN). But all pupils are capable of making progress and it is important that schools are given recognition for the work that they do with all their pupils.

We measure the progress that individual pupils have made between tests when they are in Year 2 (KS1), generally aged 7, and tests taken when they are in Year 6 (KS2) and generally aged 11. We call this the value added measure. Value added measures are intended to allow fairer comparisons between schools with different pupil intakes.

For example, school A might show higher percentages of pupils achieving Level 4 and above than school B. But school A's pupils may have done far better in their KS1 tests than school B's. For the value added measure, each school's pupils are compared individually with other pupils with similar KS1 test results. If they do better than the median - or middle - performance of those other pupils in their KS2 tests, the value added will be positive; if less well than those other pupils, it will be negative. All the individual pupil scores, positive and negative, are added together to form the school's measure.

If school A's pupils generally made less progress than the average for pupils with similar KS1 results, and school B's pupils generally made more progress than the average for pupils with similar KS1 results, then school B will have higher value added than school A, even though its percentage achieving Level 4 and above at KS2 is lower.

The KS1 to KS2 value added measure

We base each pupil's value added score on a comparison between their KS2 performance and the median - or middle - performance of other pupils with the same or similar results at KS1. The individual pupil scores are averaged to produce the school level VA measure. This number is presented as a number based around 100. This indicates the value the school has added on average for their pupils. Further information on how a value added score is calculated for a pupil and how the value added measure is calculated for a school can be found in the Value Added Technical Information section on the website.

Interpretation of a school's value added measure

The value added scores are shown as a measure based around 100. Measures above 100 represent schools where pupils on average made more progress than similar pupils nationally, while measures below 100 represent schools where pupils made less progress.

For KS1 to KS2 value added, a measure of 101 means that on average each of the school's pupils made one term's more progress between KS1 and KS2 than the median - or middle value - for pupils with similar KS1 attainment. A score of 99 means that the school's pupils made a term's less progress.

What a school's value added measure tells you

Mainstream Schools

As a guide:

• at KS1 to KS2, for schools with 30-49 pupils in the value added measure, measures of 99.4 to 101.2 represent broadly average performance, while for schools with 50+ pupils, measures of 99.6 to 101.0 are broadly average.

When comparing the measures for two schools:

• at KS1 to KS2 when comparing schools with cohorts of about 30 pupils, differences of up to 1.2 should not be regarded as significant, while for schools with about 50 pupils, differences up to 0.9 should not be regarded as significant.

Special schools

Particular care should be taken with the results for special schools and other schools where cohort sizes are small. For example, for special schools with 11 pupils included in the value added measure (remembering that the VA measure and KS2 results are not published for schools with 10 pupils or less), only measures of below 99.6 or above 101.6 are likely to be significantly different from the average. When comparing special schools with cohorts of about 11 pupils, differences of up to 1.5 should not be regarded as statistically significant.

As a guide:

• at KS1 to KS2, for special schools with 20 pupils in the value added measure, scores of 99.8 to 101.4 are broadly average.

When comparing the measures for two schools:

• at KS1 to KS2, when comparing special schools with cohorts of above 20 pupils, differences of up to 1.1 should not be regarded as statistically significant.

Value Added Profiles
By looking at the table below, you can see how the VA measure for a school compares to other schools nationally.

Coverage

The coverage column shows the percentage of pupils eligible for KS2 assessment included in the value added calculation and gives some indication of schools where the value added measure may be unrepresentative. A low percentage means that information was not available to calculate the value added scores of many of the school's pupils, and so these pupils could not be included in the value added calculation. Where coverage is less than 50%, the value added measure has not been published.

More detailed information about how the value added measure and the coverage percentage have been calculated can be found in the Value Added Technical Information section on the website.

Future developments to value added measures

As explained, the value added measures in the current Tables take account of prior attainment (result at end of previous key stage), which is the biggest single factor affecting pupil results. However, other factors outside a school's control, such as gender, mobility and levels of deprivation, have been observed to have a further impact on pupil results, even after allowing for prior attainment. To take these into account requires a more complex model of value added, which we are in the process of developing and introducing for use by the Department and Ofsted. We call this Contextual Value Added (CVA).

The 2005 Pupil Achievement Tracker and Ofsted's PANDA reports both include CVA measures. In future years we will be bringing CVA measures into the Achievement and Attainment Tables. We are piloting these with secondary schools this year, so that they can be in the Secondary Tables in 2006. We will be piloting them with primary schools next year, so that they can be in the Primary Tables in 2007. Further information on the Contextual Value Added Pilot will be published on the Tables website: www.dcsf.gov.uk/perfomancetables in early 2006.