Table 3. Means and standard deviations for measures of covariates and mathematical achievement.

		Mathematics		Literature
	Theoretical maximum	Mean	Std Dev	Mean	Std Dev
Time 1 RAPM	18	9.64	3.32	6.94	3.54
Time 1 CRT intuitive (reverse scored)	3	1.79	1.14	.89	.85
Time 1 Mathematics	15	4.86	1.59	3.50	.97
Prior academic attainment	–	66.45	9.78	61.53	14.03
Time 2 RAPM	18	10.64	2.93	7.32	3.15
Time 2 CRT intuitive (reverse scored)	3	1.98	1.02	1.11	1.02
Time 2 Mathematics	15	6.95	1.94	3.19	.57

Units are number of correct responses except for prior academic attainment, which is sum of grades for all GCSEs where A* = 8, A = 7, B = 6 etc.