Important: Read this before posting to this forum

  1. 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.
  2. 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
  3. Before asking a question on the forum, users are kindly requested to follow these steps:
    1. Check that the same issue has not already been addressed in the forum - there is a search tool.
    2. 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
    3. Check the frequently asked questions section on the Apollo website, which discusses some common issues/failures. Please see http://www.apollochoicemodelling.com/faq.html
    4. Make sure that R is using the latest official release of Apollo.
  4. If the above steps do not resolve the issue, then users should follow these steps when posting a question:
    1. provide full details on the issue, including the entire code and output, including any error messages
    2. 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 1344 matches

by stephanehess
23 Jan 2026, 12:27
Forum: Estimation results
Topic: Mixed Logit Model for BWS: differences between Apollo and Stata estimations + baseline option issue in Apollo
Replies: 3
Views: 122

Re: Mixed Logit Model for BWS: differences between Apollo and Stata estimations + baseline option issue in Apollo

Hi

they are clearly not the same model. You need to get exactly the same results for MNL. Can you show us the specification for both packages? I note the Stata one has a constant for example

Regarding item_4, this will work, but you need to include it in the utility functions of course

Stephane
by stephanehess
22 Jan 2026, 07:45
Forum: Estimation results
Topic: Unexpected sign for remuneration coefficient
Replies: 1
Views: 56

Re: Unexpected sign for remuneration coefficient

Hi

this could well have to do with your first alternative, which I assume is an opt-out? What were the levels for that?

Stephane
by stephanehess
28 Dec 2025, 14:51
Forum: Bug reports
Topic: Element gradientObs not in model object
Replies: 3
Views: 1101

Re: Element gradientObs not in model object

sorry, not at present. It should be possible in a month or so
by stephanehess
17 Dec 2025, 13:36
Forum: Bug reports
Topic: Element gradientObs not in model object
Replies: 3
Views: 1101

Re: Element gradientObs not in model object

hi

this was in an earlier version of Apollo, and is not currently implemented. It will be added again in the near future, but requires a change to the bgw optimiser first

Stephane
by stephanehess
15 Dec 2025, 10:46
Forum: Estimation results
Topic: Difference between standard vs robust t-ratios
Replies: 1
Views: 723

Re: Difference between standard vs robust t-ratios

Hi

yes, these differences are very large, and also go in the opposite direction of what we typically see. Did you try a basic version of the model, without all the attributes?

Stephane
by stephanehess
29 Nov 2025, 13:41
Forum: Installation and updating
Topic: Error in value[[3L]](cond) : unused argument (cond) in in Hybrid MMNL Model
Replies: 1
Views: 1022

Re: Error in value[[3L]](cond) : unused argument (cond) in in Hybrid MMNL Model

Hi

apologies for the slow reply. Could you share your code and data with me outside the forum and I'll have a look for you

Stephane
by stephanehess
29 Nov 2025, 13:38
Forum: Model specification
Topic: Doubts about model specification with an alternative vs. status quo
Replies: 5
Views: 1612

Re: Doubts about model specification with an alternative vs. status quo

hi

what I mean is that you could estimate a parameter for each level, and then plot their estimates against the values and see if it looks linear

Stephane
by stephanehess
29 Nov 2025, 13:36
Forum: Model estimation
Topic: Latent Class Choice Model: NaNs produced
Replies: 1
Views: 1051

Re: Latent Class Choice Model: NaNs produced

Hi

in general, using LVs in the class allocation model is empirically difficult and often leads to issues.

In your case, I would look at those parameters for which you do not obtain classical standard errors

Stephane
by stephanehess
29 Nov 2025, 13:33
Forum: Model specification
Topic: weighted choice model
Replies: 1
Views: 806

Re: weighted choice model

Hi

no, it cannot. The weights need to be provided by the user as values

Stephane