Dear Stan developers,

Thanks for developing this fantastic program.

I am implementing MCMC for computing the posterior distribution of parameters of a cognitive model.

The data structure is like follows:

```
trial stimulus choice estimation
1 1 1 0.9
2 -2 0 -1.3
3 -3 0 -3.1
4 2 0 2.2
```

On each trial, a stimulus is shown and subjects were required to make a binary choice to decide whether the stimulus is smaller (choice=0) or larger than 0 (choice=1).

Subsequently, subjects should estimate the magnitude of the stimulus in the continuous dimension.

The likelihood of parameters given the data is the product of the normal pdf and the normal cdf:

`Likelihood[trial] = normal(...)*normal_pdf(...)`

.

An error occurred when I just coded the sampling process by the product of `normal`

and `normal_pdf`

.

Can Stan implement MCMC with that likelihood?

Thanks!