Pseudo-R2 (Nakagawa, & Schielzeth, 2013) and model fit indices were obtained using the performance package (Lüdecke et al. 2021) in R (R Core Team, 2017). A series of likelihood-ratio tests were used to determine if including the age-specific PGS and/or the common factor PGS as predictors improves model fit above a model with covariates only. The model with just covariates is referred to as the base model. Contrasts were drawn between the effect size for the age-specific PGS and the common factor PGS using a Z-test of the null hypothesis that two regression coefficients are equal (Paternoster et al. 1998).
