Analyses of seasonal variation in size of brain regions in Poland
and Germany
To analyze the variation in volume of brain regions between stages of
Dehnel’s Phenomenon, locations and sexes we used ANOVA for each brain
region separately, with size corrected volume of the brain region as
response variable and age, location and sex and their interactions as
explanatory variables. Here, we included sex in the model based on the
significant effect we had previously found on the seasonal changes of
some brain regions in Radolfzell (Lázaro et al. , 2018b). To tease
apart the influence of season, geographic difference, and sexual
dimorphism, we did pair-wise comparisons between the factors’ levels
using Tukey tests for multiple comparisons.
All analyses were performed in R 3.5.0 (R Core Team, 2015).