Code:

```
set.seed(42)
n <- 100
df <- tibble(
group_a_pre = rnorm(n, mean=0, sd=1),
group_b_pre = rnorm(n, mean=50, sd=10),
group_c_pre = rnorm(n, mean=5, sd=2),
group_a_post = rnorm(n, mean=0.36, sd=1.2),
group_b_post = rnorm(n, mean=55, sd=13),
group_c_post = rnorm(n, mean=4.4, sd=2.3)
)
```

I have the following questions:

- Would I use a two-way ANOVA (factors being group and treatment), or would I use one-way ANOVA with group as the only factor, transforming the dependent variable to the difference between pre- and post-treatment?
- I assume I would z-transform the values in each group? For z-transformation, e.g., for group a, would I z-transform e.g., group_a_pre and group_a_post separately (based on the mean and standard deviation in each of the two vectors) or would I perform the transformation based on the overall mean and standard deviation for c(df$group_a_pre, df$group_a_post)?