My son passed and is a May birthday, My daufgter passed 3 years ago and is August (as are 2 of her friends), but I also know 2 of my son's friends also passed yesterday and are February and October. I think the idea that it is easier to pass if you are older comes from the premise that you are more mature, have has a longer time on this planet (
) to absorb vocabulary and ideas etc... To even this up a bit they award extra marks to the youngest. It is a large statistical group (11,000+) and the stats are therfore considered quite reliable. I think it is something like - if all the September children average 120, and all the January children average 118 and all the June children average 116, those January children are given 2 extra marks and those June children 4 extra ... and so on. It may not be quite as crude as this but I believe this is the intended outcome.