Compare your grade against class averages.
A raw score means little without the distribution behind it. The standard score expresses how many standard deviations you sit above the class mean, which is what actually determines relative standing: 78 against a mean of 71 with a spread of 9 is a z of about 0.78, roughly the 78th percentile. Comparing this cohort's mean against the module's historical mean is the separate grade-inflation check — if this year's mean is well above history, an identical raw score represents a weaker relative performance than it would have previously, which matters when your transcript is read alongside older ones.
Standard score
z = (your score - class mean) / class standard deviation
Inflation check
Inflation points = this cohort's mean - historical mean for the module
An illustrative estimate only. Grading scales, GPA weighting, honours thresholds and progression rules are set by your institution and vary between programmes and academic years. Confirm all figures with your course handbook, registry or academic adviser before relying on them for any academic decision.
Because it accounts for both the difficulty of the assessment and the spread of the cohort. A 78 in a class averaging 71 with tight spread is a strong result; the same 78 in a class averaging 76 with wide spread is unremarkable. Only the standard score captures that.
It compresses the top of the distribution, so distinguishing yourself becomes harder while your raw mark looks better. It also makes your transcript harder to compare against older cohorts, which is why some institutions now report cohort means alongside individual marks.