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WTP space results - means are negative or NANs produced

Ask questions about the results reported after estimation. If the output includes errors, please include your model code if possible.
Simone R
Posts: 8
Joined: 15 Feb 2022, 11:16

Re: WTP space results - means are negative or NANs produced

Post by Simone R »

Hi Stephane,

I ran the model in preference space with 3000 Sobol draws without any issues; LL: -2733.08

Simone
stephanehess
Site Admin
Posts: 974
Joined: 24 Apr 2020, 16:29

Re: WTP space results - means are negative or NANs produced

Post by stephanehess »

Simone

looking at this, it's clear that your models with 1000 and 4000 draws just didn't really move away from the log-likelihood at starting values, so they immediately got stuck in a hole. Were you using the same starting values in all these models?

Stephane
--------------------------------
Stephane Hess
www.stephanehess.me.uk
Simone R
Posts: 8
Joined: 15 Feb 2022, 11:16

Re: WTP space results - means are negative or NANs produced

Post by Simone R »

Hi Stephane,

yes I used the same starting values for the models with 1000, 2000, 2100, and 4000 draws. Since I only got good results without NANs or saddle point convergence for the models in the 2000-2100 draws range, I then used the results of the model with 2100 draws as starting values to run the model with 3000 draws to test whether that would improve the results when I increase the draws.

Simone
stephanehess
Site Admin
Posts: 974
Joined: 24 Apr 2020, 16:29

Re: WTP space results - means are negative or NANs produced

Post by stephanehess »

Simone

more draws is always better. If your SLL with the same values is worse with more draws, then that doesn't mean that more draws is worse. It just shows that the approximation of the true LL (remember that you are using the SLL, simulated LL) is less accurate with fewer draws

Stephane
--------------------------------
Stephane Hess
www.stephanehess.me.uk
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