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 1042 matches
- 10 Jul 2020, 15:58
- Forum: Estimation results
- Topic: Could the LL of a full model worse than that for the reduced model?
- Replies: 12
- Views: 18490
Re: Could the LL of a full model worse than that for the reduced model?
Tim the sign of the correlation depends on the sign of the product of hinc_sig_20* hinc_sig_20_90. Section Section 9.2.5 in Kenneth Train's book. The Delta method can be used for this, but you'd need to work out the derivatives yourself - they're not implemented in Apollo for the standard errors. Be...
- 09 Jul 2020, 22:03
- Forum: Estimation results
- Topic: Could the LL of a full model worse than that for the reduced model?
- Replies: 12
- Views: 18490
Re: Could the LL of a full model worse than that for the reduced model?
Hi Tim I've looked into your model in detail and I believe I have found the reason this is happening. In your base specification, you use the same coefficient whether the treatment is 20 or 90. In your more general model, you use separate parameters. Now, you see that in the MNL model, the more gene...
- 09 Jul 2020, 21:11
- Forum: Errors during model validation and/or estimation.
- Topic: Errors when using sobol draws in RPL
- Replies: 3
- Views: 6271
Re: Errors when using sobol draws in RPL
Hi Tim thanks for sharing the code and data with me which allowed me to investigate this. On my machine, the code runs fine with Sobol and with other draws. The error you are getting is actually not by Apollo but by randtoolbox which is called by Apollo for Sobol draws. Can I suggest that in the fir...
- 08 Jul 2020, 22:29
- Forum: Model specification
- Topic: Binary/Multinomial logit in the measurement model for HCM
- Replies: 3
- Views: 6327
Re: Binary/Multinomial logit in the measurement model for HCM
Hi Richard on point 1, what you do is indeed the easiest and best way of doing it. You could use the same list for the different components, but you would need to reset it in between each component (so you start with an empty one). While that would save a little memory compared to creating new lists...
- 07 Jul 2020, 22:31
- Forum: Bug reports
- Topic: Get predictions from the model with many alternatives
- Replies: 3
- Views: 12087
Re: Get predictions from the model with many alternatives
Hi Houman
thanks, this was a bug. This has been fixed in v.0.1.1 which you can download from the website (http://www.apollochoicemodelling.com/code.html)
Best wishes
Stephane
thanks, this was a bug. This has been fixed in v.0.1.1 which you can download from the website (http://www.apollochoicemodelling.com/code.html)
Best wishes
Stephane
- 03 Jul 2020, 21:18
- Forum: Estimation results
- Topic: Could the LL of a full model worse than that for the reduced model?
- Replies: 12
- Views: 18490
Re: Could the LL of a full model worse than that for the reduced model?
Tim that's a much larger difference in fit than one would expect with different draws but is in line with recent tests I've done on antithetic draws and changing signs of sigmas. What happens when you use your model with different draws, but use the results from the reduced model as starting values ...
- 03 Jul 2020, 15:33
- Forum: Estimation results
- Topic: Could the LL of a full model worse than that for the reduced model?
- Replies: 12
- Views: 18490
Re: Could the LL of a full model worse than that for the reduced model?
Tim I wasn't necessarily implying that you should use the same draws for increases and decreases, but that this could be a reason for the difference in fit. Using different draws arguably makes more sense, but let's try and understand what you're seeing a little better. 1. What draws are you using, ...
- 01 Jul 2020, 22:19
- Forum: Estimation results
- Topic: Could the LL of a full model worse than that for the reduced model?
- Replies: 12
- Views: 18490
Re: Could the LL of a full model worse than that for the reduced model?
Hi Tim let us assume you have the following situation: model 1: V = beta_x * x + ... model 2: V = beta_xinc * x_inc + beta_xdec * x_dec + ... where x_inc = (x>x0)*(x-x0) and x_dec = (x<x0)*(x-x0) not that in this notation, x_dec will be negative, which will help us with the comparison As only differ...
- 01 Jul 2020, 13:17
- Forum: Estimation results
- Topic: Could the LL of a full model worse than that for the reduced model?
- Replies: 12
- Views: 18490
Re: Could the LL of a full model worse than that for the reduced model?
Tim
could you please also share the output?
Thanks
could you please also share the output?
Thanks
- 28 Jun 2020, 16:36
- Forum: Errors during model validation and/or estimation.
- Topic: Errors when using sobol draws in RPL
- Replies: 3
- Views: 6271
Re: Errors when using sobol draws in RPL
Hi Tim
Could you please share your code and the full output you see so we can investigate?
Thanks
Stephane
Could you please share your code and the full output you see so we can investigate?
Thanks
Stephane