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Progress scores 2018: methodology changed to reduce the impact of outliers

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The Department for Education (DfE) is refining the methodology used to calculate school progress scores for 2018 in order to reduce the disproportionate impact of the most extreme pupil level progress scores. This change is a result of NAHT's work in raising and discussing the concerns of members with the DfE about the impact of the individual progress scores of these outlying students.

The refinement introduces a limit on how negative a pupils progress score can be when calculating the school average. They are not setting a maximum limit on how positive a pupils progress score can be as there are much smaller numbers of extremely positive progress scores that have a disproportionate impact than extremely negative ones.

Where a pupil's score is more negative than the minimum score, the minimum score will replace the pupil's original progress score when calculating a school's progress average.

The minimum scores will be fixed at a set number of standard deviations below the mean so that approximately 1% of pupils are identified nationally (we anticipate this will normally be no more than one or two pupils in any school).

As such, predicting which pupils will, and will not, have their score affected by this methodology change, in advance of progress scores being made available, will not be possible. The exact minimum progress scores will be confirmed in the autumn, once we have the 2018 progress data.

The adjusted progress scores will be the headline measures but they will also publish the unadjusted progress scores, within the underlying data, for transparency.

First published 23 July 2018