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. This may take a day or two at busy times. There is no need to submit the post multiple times.
Search found 18 matches
- 20 Jan 2023, 19:25
- Forum: Estimation results
- Topic: huge difference between results from a WTP-space and Preference-space model
- Replies: 3
- Views: 4033
Re: huge difference between results from a WTP-space and Preference-space model
Hi Stephane, Thank you for your reply. I agree that the positive cost coefficient is a bit worrying. Indeed, the cost is negative but not significant in the simplest MNL preference-space model (model 1). For the MNL WTP-space model, I did try a negative starting value for the cost parameter, but the...
- 31 Dec 2022, 15:13
- Forum: Estimation results
- Topic: huge difference between results from a WTP-space and Preference-space model
- Replies: 3
- Views: 4033
huge difference between results from a WTP-space and Preference-space model
Dear Stephane, Thank you very much for inventing the Apollo. I’m also the attendees of your previous summer and winter DCE courses. I was estimating a MMNL WTP space model and had a problem. The DCE Attributes: h (health, number hospital admissions due to air pollution), v (number of bad visibility ...
- 06 Jun 2022, 17:40
- Forum: Errors during model validation and/or estimation.
- Topic: Error "Some utilities for model component "MNL" contain values that are not finite numbers!"
- Replies: 1
- Views: 1746
Error "Some utilities for model component "MNL" contain values that are not finite numbers!"
Dear Stephane, I was estimating a RPL model with a non-linear specification in one of the attributes. The DCE Attributes: air, flood, ObjCert, largetrees, mixedtrees, cost Available options: 2 alternatives + 1 status quo The model The nonlinear part is specified as: R*=(exp(-((-log(R))^gamma)))), wh...
- 11 Feb 2021, 16:15
- Forum: Model estimation
- Topic: WTP-space estimates in latent class context
- Replies: 14
- Views: 19405
Re: WTP-space estimates in latent class context
Hi Stephane, Thank you for the solution. I actually wanted to ask a similar question regarding different results obtained from preference-space and WTP-space approach, but your solution solves my problem quite well. Actually, the above problem happens in my situation even when I use the most basic M...
- 25 Jan 2021, 20:34
- Forum: Errors during model validation and/or estimation.
- Topic: Errors when estimating a LC model with random components allowed for one of the classes
- Replies: 4
- Views: 7363
Re: Errors when estimating a LC model with random components allowed for one of the classes
Hi Stephane,
Thank you very much for your email and David's solution. Also thank you for reminding me reading the corresponding section in the manual which actually helps to solve my problem.
Thank you again.
Best wishes,
Tim
Thank you very much for your email and David's solution. Also thank you for reminding me reading the corresponding section in the manual which actually helps to solve my problem.
Thank you again.
Best wishes,
Tim
- 22 Jan 2021, 13:16
- Forum: Errors during model validation and/or estimation.
- Topic: Errors when estimating a LC model with random components allowed for one of the classes
- Replies: 4
- Views: 7363
Re: Errors when estimating a LC model with random components allowed for one of the classes
Dear Stephane, Thank you vey much for your help. The model runs successfully, but the standard errors for all parameters are "Inf". This actually happened before when I was running some complex models (e.g., imposing complex distributions such as Johnson SB distribution or polynomial-norma...
- 19 Jan 2021, 20:07
- Forum: Errors during model validation and/or estimation.
- Topic: Errors when estimating a LC model with random components allowed for one of the classes
- Replies: 4
- Views: 7363
Errors when estimating a LC model with random components allowed for one of the classes
Dear Stephane and David, Thank you very much for inventing the Apollo package and creating the forum allowing our users to communicate. I recently run a latent class model, but allow for inter-individual heterogeneity only within one of the classes (i.e., preferences are assumed to be non-random in ...
- 18 Jul 2020, 21:39
- Forum: Errors during model validation and/or estimation.
- Topic: An error when estimating nonlinear utility specification
- Replies: 3
- Views: 5495
Re: An error when estimating nonlinear utility specification
Dear Stephane, Yes I had errors when running apollo_inputs = apollo_validateInputs(), but I have solved the problem; it was a small mistake - I forgot to turn on the mixing=TRUE at the start. I can confirm that the non-linear specification can be run successfully using MMNL. Thank you again for your...
- 18 Jul 2020, 13:59
- Forum: Errors during model validation and/or estimation.
- Topic: An error when estimating nonlinear utility specification
- Replies: 3
- Views: 5495
An error when estimating nonlinear utility specification
Dear Stephane, Thank you for inventing the Apollo package and answering my past questions. I have encountered an error when estimating a nonlinear utility specification using MMNL. Description of my model: I have a health attribute (h) and a probability attribute (p) associated with the health outco...
- 10 Jul 2020, 17:16
- Forum: Estimation results
- Topic: Could the LL of a full model worse than that for the reduced model?
- Replies: 12
- Views: 18404
Re: Could the LL of a full model worse than that for the reduced model?
Hi Stephane,
Thanks a lot for your responses.
Tim
Thanks a lot for your responses.
Tim