Are we all born equal (when it comes to eleven plus !)?

Are all children born equal? To the uninitiated, the answer would be a "Yes", but as I am about to tell you, your child's birthday is more than just a day of party popper and funny hats. In the eleven plus grammar school selective system, it probably decides his fate as well !

Whats the Score?
When your child sits the eleven plus exam, the number of questions answered correctly decides the "Raw Score". If there are more than one tests, the score may be the sum of the raw scores. BUT in most cases, this score is not even published by the testing authority and certainly not used for the selection process. What you get is something called a standardized score. A standardized test score is calculated by translating the raw score into a completely different scale. This scale takes into account the pupils age and in some cases length of the test and difficulty levels.

Whats a standardized score?
When a "raw-score" is converted to "standardized-score", it is done with a view that the average score comes as 100. Pupils above average would have a standardized score higher than 100. In statistical terms

this is a normal distribution. The standard deviation here is taken as 15 implying that 68% of the pupils are within plus or minus 15 marks, i.e. 68% of the pupils who sit the test are between 85 and 115 standardized marks. Similarly, 96% of the pupils are within 2SD, i.e. between 70 and 139 marks.

To convert raw scores to standardized scores, the formula is :

S = 15(x - y)/ SD + 100
where S= Standardized score, X is pupils raw score, Y is the average raw score of entire population and SD is the standard deviation which is 15. But this equation assumes that no correction is applied to the raw scores to correct it for age allowance. It is to be noted that percentage scores are never used. This is because percentages do not take into account the average performance or the variations in the scores.

The Age Allowance
To be eligible for the eleven plus exam, the pupil should be born between 01 September and 31 August. This means that the maximum age difference between two children born on these extreme dates is a year. Invariably, the results for the older children are better. The best way to cater for this age variable would be to conduct the test at exactly the same age. Since the logistics of conducting a test on every day of the year are somewhat daunting, the clever professors have come up with an easier way - the age handicap (much like Golf !).  What it really means is that there is a table which is based on empirical data and provides the standardized-age-corrected score given the raw score and the age. Depending on the raw score, the difference between the scores of the youngest and eldest pupil can be as much as 4 marks!

The End Game
The correction for the age allowance means that the youngest and oldest children achieve the same standardized score although the younger children have a slightly lower raw score. At least thats the theory. To make things even more complex, different schools give different weightage to different subjects but thats a story for another day.

Della
http://www.11PlusDIY.co.uk