Table 1:

Linear models testing effects of treatment and other covariates on male hormone levels. Estimates use saline as the reference for treatment and Y1 as reference for year. Pre-injection T and ΔT values were log-transformed. Inclusion and exclusion of covariates determined via systematic comparison of candidate models (supplemental tables 2–4). Signficant predictors are bolded (p<0.05). Letters denote separate models.

Response variable	Predictor variable	Estimate (± SE)	F-statistic	p-value
ΔTestosterone (post minus pre-injection)
(a)	Treatment	1.37 ± 0.50	F1,65= 20.9	p<0.0001
	Date	0.0020 ± 0.0026	F1,65= 3.24	p=0.077
	Treatment*Date	−0.0077 ± 0.0034	F1,65= 5.19	p=0.026
	Mass	0.029 ± 0.016	F165= 4.05	p=0.049
Pre-injection Testosterone
(b)	Treatment	−0.247 ± 0.20	F1,65= 1.27	p=0.26
	Date	−0.017 ± 0.011	F1,65=5.62	p=0.021
	Year	0.49 ± 0.24 (Y2)	F2,65=3.08	p=0.053
		−0.50 ± 0.26 (Y3)
Post-injection Corticosterone
(c)	Treatment	6.11 ± 9.62	F1,33=0.40	p=0.53