# Providing initial values in init\_params for compositional sampling

**URL:** <https://discourse.julialang.org/t/providing-initial-values-in-init-params-for-compositional-sampling/107348>\
**Category:** General Usage\
**Tags:** question, turing\
**Created:** [December 8, 2023, 9:47pm UTC](https://discourse.julialang.org/t/providing-initial-values-in-init-params-for-compositional-sampling/107348 "2023-12-08T21:47:00Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![ph-rast](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/ph-rast/32/204754_2.png) [@ph-rast](https://discourse.julialang.org/u/ph-rast)\
**Post date:** [December 8, 2023, 9:47pm UTC](https://discourse.julialang.org/t/providing-initial-values-in-init-params-for-compositional-sampling/107348/1 "2023-12-08T21:47:00Z")

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Hi there,

when I’m passing initial values `init_vals = [A, init_beta, init_eta, init_sigma, init_z]` to the `init_params` argumenet in `sampling()` everything works as expected:  
`chain = sample(model, HMC(), MCMCThreads, ... , init_params = Iterators.repeated(init_vals) )`

When I extend the model to include a Bernoulli on the `ss` parameter I change the sampling statement to:  
`chain = sample(model, Gibbs(HMC(), MH(:ss)), ... )`

How do I include the initial value for `ss`?  
Adding it into the `init_vals` vector does not seem to work.  
It returns  
`nested task error: Provided initial value doesn't match the dimension of the model`  
This is not surprising, as the `init_ss` can’t be assigned to just the MH sampler.

Any insights?

See [this](https://discourse.julialang.org/t/initialising-parameter-values-with-compositional-sampling-in-turing-jl/36494) unanswered related question