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 11 matches
- 05 Dec 2023, 10:26
- Forum: Post-estimation analysis/use of results
- Topic: Combining output from apollo_prediction lists
- Replies: 1
- Views: 32480
Combining output from apollo_prediction lists
Dear Apollo team, I am running model predictions / scenario analysis as per the manual and was wondering if there is a way to combine results as I have ~30/40 scenarios to run. The default “summary” argument/ setting for apollo_prediction saves the mean, SD and 95%CI which is the information from ea...
- 19 Oct 2023, 11:22
- Forum: Models and estimation
- Topic: A question on WTP estimation
- Replies: 2
- Views: 36429
A question on WTP estimation
Dear Stephane, I have looked in the literature (including the Hensher textbook and your recent articles on WTP) and cannot find answers to my questions below. I was hoping you might be able to shed some light on them given your expertise and the fact this can be done in Apollo so might be relevant t...
- 05 Oct 2023, 18:41
- Forum: Post-estimation analysis/use of results
- Topic: post-estimation scenario analysis
- Replies: 4
- Views: 9618
Re: post-estimation scenario analysis
Dear Stephane, Thank you for your reply, the database backup works, however I am having some issues with working with predictions at estimates. In the Apollo manual (Fig. 9.9), when running predictions, the mean change calculated after you change the cost of rail by 1% corresponds with the relative ...
- 22 Sep 2023, 14:50
- Forum: Post-estimation analysis/use of results
- Topic: post-estimation scenario analysis
- Replies: 4
- Views: 9618
Re: post-estimation scenario analysis
As an extension of my question above, I have the following code which might better illustrate what I am trying to do and an example scenario. Where I have added "[Q1]" to the code, I am trying to set up a scenario for a model prediction where one of my categorical variables is fixed at lev...
- 20 Sep 2023, 11:36
- Forum: Post-estimation analysis/use of results
- Topic: post-estimation scenario analysis
- Replies: 4
- Views: 9618
post-estimation scenario analysis
Dear Stephane & David, I have some questions on producing hypothetical scenarios post-estimation as an extension of predictions. I have looked through the manual, examples and forum - the only thing I can find was a previous similar question on the forum which was never answered (here: http://ww...
- 19 Sep 2023, 14:03
- Forum: Post-estimation analysis/use of results
- Topic: Apollo_deltaMethod expression for non-model parameters
- Replies: 1
- Views: 5737
Apollo_deltaMethod expression for non-model parameters
Dear Stephane, I am using the Apollo_deltaMethod to calculate SE for Marginal Rates of Substitution between a continuous variable (time) and a categorical variable with levels ("high", "moderate", "low" and "very low"(the reference category). I have used the d...
- 14 Aug 2023, 17:09
- Forum: Estimation results
- Topic: Error: Non-valid user-provided bgw_setting setting name detected: "writeIterMode"."
- Replies: 4
- Views: 6514
Re: Error: Non-valid user-provided bgw_setting setting name detected: "writeIterMode"."
Hi David,
Thanks for your quick reply. This seems to have fixed it - the model now runs!
Thanks again,
Rob
Thanks for your quick reply. This seems to have fixed it - the model now runs!
Thanks again,
Rob
- 14 Aug 2023, 10:58
- Forum: Estimation results
- Topic: Error: Non-valid user-provided bgw_setting setting name detected: "writeIterMode"."
- Replies: 4
- Views: 6514
Error: Non-valid user-provided bgw_setting setting name detected: "writeIterMode"."
Dear Prof. Hess, I have previously ran successfully, an MNL model on Apollo version v0.2.9 (about 6 weeks ago) which I used to obtain priors. I have now come back with full data and run the same model again (albeit different data).During this, I was prompted to update to Apollo v0.3.0 but since upda...
- 10 Jul 2023, 16:58
- Forum: Model specification
- Topic: Model spec for multiple interactions between categorical attributes for DCE with scenario attributes
- Replies: 3
- Views: 5373
Re: Model spec for multiple interactions between categorical attributes for DCE with scenario attributes
Dear Prof. Hess, Thank you for your reply. The rationale behind keeping QOL, LIFE and BENEFIT generic across alternatives was because during piloting, almost everyone said there was too much information to make a choice. We found that keeping the scenario attributes constant between alternatives hel...
- 06 Jul 2023, 16:21
- Forum: Examples (existing and requests for new ones)
- Topic: Dummy coding of categorical variables in MNL_SP example.
- Replies: 1
- Views: 4943
Dummy coding of categorical variables in MNL_SP example.
Dear Prof. Hess, This might be a simple question, but might also be useful also to others starting out in Apollo. In the Apollo MNL_SP model example, there is a categorical attribute for service (service_rail), which has 4 levels: 1 for no-frills, 2 for wifi, 3 for food, 0 if not used. Also in this ...