# Simple model Parse Errors

**URL:** <https://discourse.mc-stan.org/t/simple-model-parse-errors/3249>\
**Category:** Modeling\
**Tags:** specification\
**Created:** [February 9, 2018, 9:15pm UTC](https://discourse.mc-stan.org/t/simple-model-parse-errors/3249 "2018-02-09T21:15:05Z")\
**Posts on this page:** 1\
**Showing post:** 9

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**Author:** ![innuo](https://avatars.discourse-cdn.com/v4/letter/i/dec6dc/32.png) [@innuo](https://discourse.mc-stan.org/u/innuo)\
**Post date:** [February 11, 2018, 12:02am UTC](https://discourse.mc-stan.org/t/simple-model-parse-errors/3249/9 "2018-02-11T00:02:52Z")

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Thanks for the tip. I will read the Stan manual to see if I can follow the examples about using censoring for my problem.

I have a more general question about modeling processes of the following type. Assume

```
z1 ~ Normal(mu1, sigma1)
z2 ~ Normal(mu2, sigma2)
x = f(z1, z2)

```

where `f` is a deterministic function.

If I observe `x` and am trying to infer `E[z1, z2 | x]`, how do I go about modeling this in Stan?

Looks like I’ll have to put `x` in the data section, but when I try doing that but declare `x = f(z1, z2)` in the model section I get the “cannot assign variable outside declaration block” error.

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