The package 'r2glmm' in R calculated the "semi-partial R squared" of each fixed predictor in a mixed effects model. The package describes this as
"The semi-partial R squared statistic corresponds to a select subset of fixed predictors in a fitted model and measures the relative increase in association between the dependent and independent variables resulting from the inclusion of the specified subset."
I am wondering if this is synonymous with the squared semi-partial correlation for each predictor?
Note that the package calculates the Marginal R squared of the model as a whole. I wonder if it does this for the fixed predictors as well, which would explain the difference.