Table 2.

Correlations between KS deciles

	KS1	KS2	KS3	KS4
KS1	1
KS2	0.78 (0.78 to 0.79)	1
KS3	0.67 (0.65 to 0.68)	0.81 (0.81 to 0.82)	1
KS4	0.63 (0.61 to 0.64)	0.73 (0.72 to 0.74)	0.73 (0.72 to 0.74)	1

Numbers are correlation coefficients (95% CI).

All p values <0.001.

KS, Key Stage.