Table 1.

Predictors of urinary neopterin levels in 502 samples from 70 sexually mature chimpanzees (N_males = 34, N_females = 36).

Term	β	SE	DF	p
Intercept	− 1.373	0.011
Age (years)	0.026	0.008	58.646	0.002
Sex (male)	0.053	0.015	71.596	0.001
Time of day	− 0.024	0.005	488.821	< 0.001
Sine (Julian date)	0.001	0.007	484.998	0.847
Cosine (Julian date)	0.065	0.010	67.875	< 0.001

SE  standard error, DF degrees of freedom estimated by Satterthwaite approximation.

Bold font denotes significance. Please note that urinary neopterin levels were Box–Cox transformed prior to analysis.