The partial eta-squared can be calculated with the etasq
function in heplots
package
library(car)
mod <- Anova(lm(a ~ 1),
idata = idata,
type = 3,
idesign = ~Caps*Lower)
mod
library(heplots)
etasq(mod, anova = TRUE)
Since you are asking about the calculations:
From ?etasq
: 'For univariate linear models, classical η^2 = SSH / SST and partial η^2 = SSH / (SSH + SSE). These are identical in one-way designs.'.
If you wish to inspect the code for the calculations of η^2 for a model with a class
as in the example, you may use getS3method(f = "etasq", class = "Anova.mlm")
.