# What do the Difference and Variance columns mean in Series Comparison?

**KS4**

Difference: The direction of the 'spread' of results expressed in points. Sum of all points differences for all pupils divided by number of pupils. A difference of 6 is 1 GCSE grade, and so a difference of 3 is +0.5 of a grade in a GCSE subject.

Because this tool works in QCA points, the difference between a 5 and a 6 in a GCSE number grade qualification will show as 6. This will correct itself over time as we look to replace the underlying the currency across all tools to 9-1 in early 2017.

Variance: The 'spread' of results expressed in points - this figure will always be positive. 2 pupils, 1 moving from a C to an A and the other B to a C are expressed as differences of 12 and 6. Divide total by number of pupils. 18/2 = 9. This indicates a variance of 1.5 grades in a GCSE subject (where the difference between each grade is 6 points, except from a U to a G which is 16)

**KS5 (2016 onwards)**

Variance: The 'spread' of results expressed in points - this figure will always be positive. 2 pupils, 1 moving from a C to an A and the other B to a C are expressed as differences of 20 and 10. Divide total by number of pupils. 30/2 = 15. This indicates a variance of 1.5 grades in an A Level subject.

Difference: The direction of the 'spread' of results expressed in points. Sum of all points differences for all pupils divided by number of pupils. Using example above, 20 + -10 = 10, /2 = 5. 5 indicates a difference of +0.5 of a grade in an A Level subject.