Hey I would need some help with the lme4 package. I'm not allowed to share the original data, but I will give you a similar code:

```
time <- as.factor(c(1,2,1,2,1,2,1,2))
grad <- as.factor(c(0,0,1,1,2,2,3,3))
group <- as.factor(c(rep("F",9), rep("P",9)))
v_df <- data.frame(matrix(rnorm(18*8),nrow=18))
v_y <- unlist(v_df)
v_subject <- rep(rownames(v_df), ncol(v_df))
v_group <- rep(group, ncol(v_df))
v_time <- rep(time, each=nrow(v_df))
v_grad <- rep(grad, each=nrow(v_df))
y <- summary(lmer(v_y ~ v_group:v_time+v_group:v_grad+(v_grad|v_time)+(1|v_subject)))
```

The categories of my fixed effects in `y`

look as follows: (Intercept), v_groupF:v_time1, v_groupP:v_time1, v_groupF:v_time2, v_groupF:v_grad1, v_groupP:v_grad1, v_groupF:v_grad2, v_groupP:v_grad2, v_groupF:v_grad3, v_groupP:v_grad3.

My question is: Where is my category "0" in `v_grad`

? Is `v_groupP:v_time2`

my intercept?

Every advice is highly appreciated!