The "attainment gap" is a measure of the difference between the grades of the top 20% better-off students and those who live in the bottom fifth of the Scottish Index of Multiple Deprivation (SIMD). The way SIMD is used has been changed this year which resulted in some revision of previous figures. The latest stats show that at National 5, the gap is 15.6 percentage points, down from 16.4. That's because 86.6% of better-off students got an A to C grades this year as opposed to 71% of those in the most deprived areas. At Higher, the gap is 15.9 percentage points, down from 16.8 last year.