Table 1.

Results for the fixed effects from mixed-model analysis of each of the indicated predictors on clutch size

Effect	Estimate	Standard error	KR degrees of freedom	t value	P
Intercept	5.5537	0.04432	54.9	125.32	<0.0001
Laydate	−0.02956	0.001884	2,649	−15.68	<0.0001
(Laydate)2	−0.00022	0.000109	2,722	−2.03	0.0421
Latitude	0.05036	0.009067	49.5	5.55	<0.0001
(Latitude)2 × April–May temperature	−0.00101	0.000402	236	−2.50	0.0129
(Longitude)2	−0.00043	0.000097	60.7	−4.45	<0.0001
(Longitude)2 × April–May temperature	0.000047	0.000028	75.2	1.66	0.1019
Elevation	0.000383	0.000073	49.7	5.27	<0.0001

All predictors in this analysis were centered around their overall mean before the test. Degrees of freedom are estimated for each predictor with the Kenward–Roger (KR) procedure. For details on model simplification see Results.