Why is account taken of a pupil's age?
Nearly all pupils taking secondary selection tests during a particular school year are born between 1st September and 31st August of the following year, which means that the oldest pupils are very nearly 12 months older than the youngest. Almost invariably in ability and attainment tests, older pupils achieve slightly higher raw scores than younger pupils. In order not to disadvantage pupils who were born in, say, June, July or August rather than the previous September or October, the tests should, in theory, be taken by the pupils when they reach a particular exact age, e.g. 10 years 8 months. However, this is completely impractical, as it would take a full 12 months to administer the 11+ tests for a typical year group. So, instead, an allowance is included in the standardised scores that enables all the pupils to take the test on the same day, eliminating the age differential. Consequently, there is no advantage or disadvantage according to the month of birth. In effect, pupils are only being compared with other pupils of exactly the same age as themselves (measured to the nearest month).