Important: Read this before posting to this forum
- 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.
- 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
- Before asking a question on the forum, users are kindly requested to follow these steps:
- Check that the same issue has not already been addressed in the forum - there is a search tool.
- 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
- Check the frequently asked questions section on the Apollo website, which discusses some common issues/failures. Please see http://www.apollochoicemodelling.com/faq.html
- Make sure that R is using the latest official release of Apollo.
- Users can check which version they are running by entering packageVersion("apollo").
- Then check what is the latest full release (not development version) at http://www.ApolloChoiceModelling.com/code.html.
- To update to the latest official version, just enter install.packages("apollo"). To update to a development version, download the appropriate binary file from http://www.ApolloChoiceModelling.com/code.html, and install the package from file
- If the above steps do not resolve the issue, then users should follow these steps when posting a question:
- provide full details on the issue, including the entire code and output, including any error messages
- 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 5 matches
- 01 Jul 2026, 17:51
- Forum: Models and estimation
- Topic: Choosing 'beta_fixed' paramters for Latent Class
- Replies: 1
- Views: 3099
Choosing 'beta_fixed' paramters for Latent Class
Hi, I'm wondering if anyone can point me toward resources that discuss selection of parameters to fix when estimating latent class. If I recall correctly, some programs automatically select parameters to fix at starting values (or zero) while Apollo allows flexibility of choice. Are their best ...
- 18 Nov 2025, 15:43
- Forum: Estimation results
- Topic: Interpretation of MXL Standard Errors using weighting
- Replies: 3
- Views: 35366
Re: Interpretation of MXL Standard Errors using weighting
Thank you for the reply! This is a curiosity more than anything, but I'm wondering if the following procedure makes sense and also might result in consistent standard errors. Admittedly, this is more of an intuitive exercise that may not hold any water.
1) Estimate/obtain sample weights using ...
1) Estimate/obtain sample weights using ...
- 16 Oct 2025, 01:16
- Forum: Estimation results
- Topic: Interpretation of MXL Standard Errors using weighting
- Replies: 3
- Views: 35366
Interpretation of MXL Standard Errors using weighting
Hi,
I am exploring the use of sample weights so that the results of a current study may be interpreted as more generalizable. The study uses a DCE to measure seafood preferences. I used CDC NHANES data to calculate appropriate sample weights using equivalent data. There are two questions I have ...
I am exploring the use of sample weights so that the results of a current study may be interpreted as more generalizable. The study uses a DCE to measure seafood preferences. I used CDC NHANES data to calculate appropriate sample weights using equivalent data. There are two questions I have ...
- 21 Jul 2025, 18:40
- Forum: Errors during model validation and/or estimation.
- Topic: Log-likelihood calculation fails at values close to the starting values!
- Replies: 2
- Views: 92490
Re: Log-likelihood calculation fails at values close to the starting values!
Thank you! I appreciate your help. After adapting the starting values and catching one other issue with the attribute definitions the MNL now converges.
And thank you for getting Apollo out the the world! It quickly became my go to for choice modeling.
Mike
And thank you for getting Apollo out the the world! It quickly became my go to for choice modeling.
Mike
- 16 Jul 2025, 20:45
- Forum: Errors during model validation and/or estimation.
- Topic: Log-likelihood calculation fails at values close to the starting values!
- Replies: 2
- Views: 92490
Log-likelihood calculation fails at values close to the starting values!
Hi,
I've been using Apollo for about 5 years now. This is the first time I've encountered the log-likelihood calculation error. I am attempting to estimate a MNL to conduct preliminary analysis on the first wave of DCE respondents collected and get starting values for MXL to be used later. After ...
I've been using Apollo for about 5 years now. This is the first time I've encountered the log-likelihood calculation error. I am attempting to estimate a MNL to conduct preliminary analysis on the first wave of DCE respondents collected and get starting values for MXL to be used later. After ...