R- Partial eta squared for repeated measures ANOVA (car package)

Question

I have a 2-way repeated measures design (3 x 2), and I would like to get figures out how to calculate effect sizes (partial eta squared). I have a matrix with data in it (called a) like so (repeated measures) ``` A.a A.b B.a B.b C.a C.b 1 514.0479 483.4246 541.1342 516.4149 595.5404 588.8000 2 569.0741 550.0809 569.7574 599.1509 621.4725 656.8136 3 738.2037 660.3058 812.2970 735.8543 767.0683 738.7920 4 627.1101 638.1338 641.2478 682.7028 694.3569 761.6241 5 599.3417 637.2846 599.4951 632.5684 626.4102 677.2634 6 655.1394 600.9598 729.3096 669.4189 728.8995 716.4605 ``` idata = ``` Caps Lower A a A b B a B b C a C b ``` I know how to do a repeated measures ANOVA with the car package (type 3 SS is standard in my field although I know that it results in a logical error.. if somebody wants to explain that to me like I'm 5 I would love to understand it): ``` summary(Anova(lm(a ~ 1), idata=idata,type=3, idesign=~Caps*Lower)), multivariate=FALSE) ``` I think what I want to do is take this p…

Accepted Answer

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")`.

R- Partial eta squared for repeated measures ANOVA (car package)

Solution

Problem