Table 7. Fitted parameters for the ordinal logistic model (see Eq 1 for how to use).

The negative regression slope β represents the improvement with age; the positive γ represents the poorer performance of boys. The model residual deviance is 2305 compared to 2635 for a model ignoring age and sex (thus with two fewer free parameters).

Parameter	Estimated value	Significance
Age regression slope β (per log10 year)	-3.079	<10−10
Effect of being male γ	+0.4152	0.002
α40|60	-5.513	<10−10
α60|100	-4.623	<10−10
α100|200	-3.639	<10−10
α200|400	-2.679	<10−10
α400|800	-2.007	<10−10
α800|Nil	-0.9797	0.003