Hi all,

I’m fitting a piecewise regression model with a random transition point, `tp`

.

I’m doing this based on data, `x_data`

, which is defined as a vector of length `N`

.

I’ve successfully used to below code to define a variable that tells me whether my data is before this transition point (`region_1`

) or after it, (`region_2`

):

```
parameters{
...
real tp; // transition point
...
}
transformed parameters {
// Introduce an indicator variable to distinguish between the 2 sides of the transition point
vector [N] region_2;
for (i in 1:N){
if (x_data[i] < tp) {
region_2[i] = 0;
} else {
region_2[i] = 1;
}
}
}
```

I wanted to develop this into a hierarchical model, with different model parameters (including `tp`

) for each different group. I need a version of my `region_2`

vector to work for this case.

My attempts to do this have so far not resulted in any samples. I believe there is a problem with how I am indexing my new `region_2`

parameter.

Please let me know if you have any experience or advice. Thanks!