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 1046 matches
- 15 May 2024, 14:59
- Forum: Model specification
- Topic: Order of parameters in apollo_beta (LC model)
- Replies: 4
- Views: 188
Re: Order of parameters in apollo_beta (LC model)
Essentially, you started the estimation at a degenerate solution, where two classes had exactly the same parameters, and you fixed the weight for the two classes to be the same. once you fix that issue, things work. The reason for the order of starting values messing things up in this case is that t...
- 15 May 2024, 14:33
- Forum: Model estimation
- Topic: Function evaluation limit exceeded.
- Replies: 1
- Views: 27
Re: Function evaluation limit exceeded.
This is likely due to numerical issues. Have you tried with a simpler model specification first, and using a subset of the data?
- 15 May 2024, 14:31
- Forum: Estimation results
- Topic: Seeking Advice on Improving MNL Model Fit with Low Rho-square
- Replies: 1
- Views: 7
Re: Seeking Advice on Improving MNL Model Fit with Low Rho-square
Hi
again, you would find answers to this in standard textbooks. In choice modelling, our emphasis is much more on relative fit by comparing different models on the same data, rather than on fit per se. Base models often have a low rho2
Stephane
again, you would find answers to this in standard textbooks. In choice modelling, our emphasis is much more on relative fit by comparing different models on the same data, rather than on fit per se. Base models often have a low rho2
Stephane
- 15 May 2024, 14:30
- Forum: Estimation results
- Topic: Queries on Using Correlation Matrix in MNL Model Estimation
- Replies: 1
- Views: 6
Re: Queries on Using Correlation Matrix in MNL Model Estimation
Hi
you would find answers to these queries in standard textbooks on choice modelling. I would use the robust covariance matrix. 0.6 is not an issue - inspecting the covariance matrix is useful to see if there are any nearly perfectly correlated parameters, but 0.6 is way off that
Stephane
you would find answers to these queries in standard textbooks on choice modelling. I would use the robust covariance matrix. 0.6 is not an issue - inspecting the covariance matrix is useful to see if there are any nearly perfectly correlated parameters, but 0.6 is way off that
Stephane
- 09 May 2024, 06:30
- Forum: Data preparation, processing and pre-estimation analysis
- Topic: Handling 'Not Available' Data
- Replies: 3
- Views: 166
Re: Handling 'Not Available' Data
Hi
your specification is correct but your results are worrying as the effect in the reference group is positive and as the income effect is not monotonic
Stephane
your specification is correct but your results are worrying as the effect in the reference group is positive and as the income effect is not monotonic
Stephane
- 09 May 2024, 06:26
- Forum: Estimation results
- Topic: Positive price coefficient in RPL model estimation
- Replies: 10
- Views: 369
Re: Positive price coefficient in RPL model estimation
Okay, in that case, Normals might be okay. In terms of computing error measures, you can have a look at this paper (DOI: 10.1016/j.trb.2013.09.010) and think about how to set this up in Apollo, but it is not precoded
- 08 May 2024, 10:09
- Forum: Estimation results
- Topic: Positive price coefficient in RPL model estimation
- Replies: 10
- Views: 369
Re: Positive price coefficient in RPL model estimation
What are your attributes?
- 07 May 2024, 15:57
- Forum: Errors during model validation and/or estimation.
- Topic: Error in estimating Latent class model with RP-SP data
- Replies: 9
- Views: 224
Re: Error in estimating Latent class model with RP-SP data
yes, having all the starting values at zero also led to an issue with the initial check of the gradients. It's always good practice to use different starting values in different classes
- 07 May 2024, 10:24
- Forum: Errors during model validation and/or estimation.
- Topic: Error in estimating Latent class model with RP-SP data
- Replies: 9
- Views: 224
Re: Error in estimating Latent class model with RP-SP data
Hi two changes are needed in your code. As apollo_combineModels is called inside the latent class model, you need P[[paste0("Class_",s)]] = apollo_combineModels(P_temp, apollo_inputs, functionality,components=c(paste0("RP_class_",s),paste0("SP_class_",s)),asList=FALSE) ...
- 07 May 2024, 07:55
- Forum: Errors during model validation and/or estimation.
- Topic: Error in estimating Latent class model with RP-SP data
- Replies: 9
- Views: 224
Re: Error in estimating Latent class model with RP-SP data
Can you share your code and data with me outside the forum, and I'll try to debug it for you