The performances of pupils at the bottom and top of the attainment "league table" are showing slight signs of improvement - with younger pupils making up more ground than older ones.
In the last school session, according to the official analysis of exam results published this week, only 4 per cent of leavers had no awards, down from 4.7 per cent the previous year and 4.6 per cent the year before. Some may have unit awards, but not a pass in the complete subject.
At the opposite end of the spectrum, the numbers achieving an Advanced Higher were up from 11.8 per cent to 12.9 per cent, against 11.1 per cent in 2001-02.
The middle of the range also made advances, with the numbers of those achieving five or more Standard grades 1-2 and Intermediate A-C passes increasing from 46.7 per cent to 49 per cent.
The figures show the perennial impact of disadvantage: 11.3 per cent of leavers who were registered for free school meals received no award in 2003-04, against 2.7 per cent for those not on free meals.
The bulletin allocates a "tariff score" to different levels of award: a Standard grade 6, for example, is worth eight points, a Higher A 72 and an Advanced Higher A 120. The score for a pupil is arrived at by adding up the total.
On this calculation, S4 pupils had an average score of 170, up from an average of 168 for 2002-03.
But there is a huge range, again reflecting the effects of affluence and disadvantage. The score for children in care in someone's home is just 41 and that for those looked after away from home is 70 (although the statisticians caution that the figures have been affected by incomplete returns).
The data can be mined to produce a rich seam of information - such as the apparent effects of the month in which a pupil was born. It appears that the youngest do better. Among last year's S4 pupils, those born after February 1989 had an average tariff score of 206. Those born before March 1988 could only manage 132.
Using the tariff system, further fascinating information is revealed on the results of white and non-white pupils, showing that Chinese, Indian and mixed race pupils outperform their white peers. Chinese pupils had the highest S4 score in 2003-04, at 225.
It also pays to be born in the remoter parts of Scotland: the average tariff was 189 compared to 163 for large urban areas.
Girls maintained their superiority, averaging a tariff score of 178 in fourth year against 162 for boys. They performed better at all exam stages, apart from the category for three or more Advanced Higher passes.