Table 1 Results of full LMMs to predict TMSC, donation period and ejaculate volume. In each model the response variables as well as abstinence period were log₁₀-transformed to normalize distributions and residuals (Supplementary Material Figures S1, S2); all continuous predictors were standardized to facilitate comparison of effects on the same scale. NA indicates interaction terms not included in the full models because the p-values were > 0.20; bold text indicates statistical significance (P < 0.05). Each model is based on 504 samples from 63 donors

Fixed effects

(Intercept)

2.83 [2.77, 2.89] < 0.001

0.52 [0.46, 0.58] < 0.001

VR used? [yes]

0.06 [0.05, 0.08] < 0.001

0.02 [0.001, 0.03] 0.04

Abstinence Period

0.00004 [–0.01, 0.01] > 0.99

0.05 [0.04, 0.06] < 0.001

VR-use x Abstinence Period

NA

NA

Age (years)

–0.02 [–0.06, 0.01] 0.24

0.015 [–0.021, 0.050] 0.42

BMI

–0.008 [–0.04, 0.03] 0.66

–0.015 [–0.050, 0.020] 0.41

Day of the year

–0.0009 [–0.01, 0.009] 0.85

0.003 [–0.006, 0.012] 0.45

Location [AAR]

0.008 [–0.09, 0.11] 0.87

0.05 [–0.05, 0.15] 0.36

Location [CPH]

0.05 [–0.04, 0.13] 0.25

0.004 [–0.08, 0.09] 0.93

Location [ODE]

0.07 [–0.04, 0.18] 0.21

0.05 [–0.06, 0.16] 0.35

Random effects

ICC

0.65

0.70

R² marginal

0.08

0.14

R² conditional

0.67

0.74