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  1. This forum is for questions related to the use of Apollo. We will answer some general choice modelling questions too, where appropriate, and time permitting. We cannot answer questions about how to estimate choice models with other software packages.
  2. There is a very detailed manual for Apollo available at http://www.ApolloChoiceModelling.com/manual.html. This contains detailed descriptions of the various Apollo functions, and numerous examples are available at http://www.ApolloChoiceModelling.com/examples.html. In addition, help files are available for all functions, using e.g. ?apollo_mnl
  3. Before asking a question on the forum, users are kindly requested to follow these steps:
    1. Check that the same issue has not already been addressed in the forum - there is a search tool.
    2. Ensure that the correct syntax has been used. For any function, detailed instructions are available directly in Apollo, e.g. by using ?apollo_mnl for apollo_mnl
    3. Check the frequently asked questions section on the Apollo website, which discusses some common issues/failures. Please see http://www.apollochoicemodelling.com/faq.html
    4. Make sure that R is using the latest official release of Apollo.
  4. If the above steps do not resolve the issue, then users should follow these steps when posting a question:
    1. provide full details on the issue, including the entire code and output, including any error messages
    2. posts will not immediately appear on the forum, but will be checked by a moderator first. We check the forum at least twice a week. It may thus take a couple of days for your post to appear and before we reply. There is no need to submit the post multiple times.

Search found 8 matches

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by duxdfx
13 Nov 2022, 00:30
Forum: Model estimation
Topic: negative standard errors of random coefficients
Replies: 1
Views: 8955

negative standard errors of random coefficients

I estimated a mixed logit model with three random coefficients (log-normal distributed). see below:
mu_log_b_prm -5.59949
sigma_log_b_prm -1.86121
mu_log_b_sub -9.10539
sigma_log_b_sub -4.87119
mu_log_b_lia -8.49144
sigma_log_b_lia 3.91300

Are these valid estimates?
by duxdfx
10 Nov 2022, 02:53
Forum: Model specification
Topic: nonlinear utility function
Replies: 1
Views: 5344

nonlinear utility function

I am trying to estimate a mixed logit model with a non-linear utility function (with risk preference parameters to identify).
Does Apollo allow me to specify and estimate a non-linear utility function?
by duxdfx
01 Feb 2022, 16:29
Forum: Model specification
Topic: latent class model
Replies: 4
Views: 10303

latent class model

Hi Stephane,

I am trying to specify a latent class model. But the class is not fixed for each individual over time. In other words, starting from one period, an individual's situation is changed, his status/group is changed. In model specification, I want to include not only individual demographic ...
by duxdfx
16 Jan 2022, 18:53
Forum: Errors during model validation and/or estimation.
Topic: Error after convergence when estimating a latent class model
Replies: 1
Views: 6653

Error after convergence when estimating a latent class model

Hi, First, thank you for all your help along the process. You have been answering several questions quickly, very helpful. Much appreciated!

the model runs and converged after 59 iterations, but some error message appears after that saying: "Error in maxOptim(fn = fn, grad = grad, hess = hess ...
by duxdfx
11 Jan 2022, 20:34
Forum: Errors during model validation and/or estimation.
Topic: error in estimating a latent class model
Replies: 1
Views: 16717

error in estimating a latent class model

Hi, I am estimating a latent class model. In estimation the following error message poped up:
"Testing influence of parameters
Error in apollo_avgInterDraws(P[["model"]], apollo_inputs, functionality) :
No Inter-individuals draws to average over!"
I appreciate your suggestions!

I attached the ...
by duxdfx
04 Jan 2022, 21:20
Forum: Errors during model validation and/or estimation.
Topic: log-likelihood calculation failed
Replies: 1
Views: 6501

log-likelihood calculation failed

Hi,

I am estimating a mixed logit model with 3 random coefficients and got the following error message:
"Error in apollo_estimate(apollo_beta, apollo_fixed, apollo_probabilities, :
Log-likelihood calculation fails at values close to the starting values!"
I tried to use the logit estimates for the ...
by duxdfx
16 Dec 2021, 14:37
Forum: Data preparation, processing and pre-estimation analysis
Topic: difference choice sets
Replies: 2
Views: 34450

Re: difference choice sets

Thanks a lot, Stephanehess! I will take a careful look and get back to you if I have questions.
by duxdfx
13 Dec 2021, 18:12
Forum: Data preparation, processing and pre-estimation analysis
Topic: difference choice sets
Replies: 2
Views: 34450

difference choice sets

In my case, for each choice situation, the choice set is slightly different, in other words, some alternatives are not available. So if I change to "wide" format, some alternative-specific attributes are NA. Can I still use Apollo to estimate the model? Thanks!

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