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. This may take a day or two at busy times. There is no need to submit the post multiple times.

Search found 190 matches

by dpalma
06 Feb 2024, 20:46
Forum: Model specification
Topic: MDCEV gamma parameterisation
Replies: 1
Views: 273

Re: MDCEV gamma parameterisation

Hi, Sorry for the delayed response. Both Stephane and I were travelling and didn't get the chance to look at the forum as often as we are used to. I am not sure if it is the same in your case, but in the example you built, the problem is that the budget is incorrect for those observations where work...
by dpalma
06 Feb 2024, 20:36
Forum: Errors during model validation and/or estimation.
Topic: Unable to compute analytical gradients
Replies: 8
Views: 5414

Re: Unable to compute analytical gradients

Hi, Sadly, Apollo cannot handle the use of the parse function and use analytical gradient. So if you use "parse", then you are forced to use numerical gradients. Looking at your code, you could avoid using "parse" by writing the utility function as follows: V[[alt]] = get(paste0(...
by dpalma
06 Feb 2024, 20:03
Forum: Model specification
Topic: Question about the specification of the MMNL_inter_intra example
Replies: 1
Views: 238

Re: Question about the specification of the MMNL_inter_intra example

Hi Shawn, It seems to me you are mixing two different things together. The first is the use of polynomial terms in the random components (which is explained in the manual), and the second, and unrelated aspect, is the use of both inter and intra draws. At least as a first step, I would advice agains...
by dpalma
06 Feb 2024, 19:53
Forum: Model specification
Topic: Are latent variables in Hybrid choice model correlated?
Replies: 7
Views: 4828

Re: Are latent variables in Hybrid choice model correlated?

Hi,

If the model looks identified, then it should be ok. We didn't find any issues with the code.

Best
David
by dpalma
06 Feb 2024, 19:45
Forum: Model specification
Topic: adding context variables in class allocation model in latent class logit model
Replies: 1
Views: 264

Re: adding context variables in class allocation model in latent class logit model

Hi Qiang,

We believe there may be a problem with the value of your explanatory variables associated to the coefficients that become zero. Could you tabulate (or summarise) the values of explanatory variables diredist1, diredist2, ..., purpose1, purpose2, etc.?

Best
David
by dpalma
06 Feb 2024, 19:40
Forum: Model estimation
Topic: Estimation of MNL and MMNL in WTP space issues
Replies: 5
Views: 776

Re: Estimation of MNL and MMNL in WTP space issues

Hi,

We looked at your new results with Stephane, and we think you should try running your WTP model again, but this time starting the b_price=-.1 (or any other small negative number).

Best
David
by dpalma
06 Feb 2024, 19:31
Forum: Model estimation
Topic: Posterior probability more than 100%?
Replies: 1
Views: 281

Re: Posterior probability more than 100%?

Hi Tim,

Just by looking at your code we cannot find any evident mistake. If you can share your code and data with us we can check in more detail. You can either send them through the forum or to D.Palma[at]leeds.ac.uk.

Best
David
by dpalma
06 Dec 2023, 15:52
Forum: Model estimation
Topic: How to change the setting of delta matrix (for complementarity)
Replies: 7
Views: 51286

Re: How to change the setting of delta matrix (for complementarity)

Hi, Sorry for the delayed response. Kamakura & Russell (1989)’s approach is what most people in choice modelling would call a latent class approach. So using their notation you have the f_ni probability, which is the class allocation probability, so the probability of individual n belonging to c...
by dpalma
06 Dec 2023, 14:09
Forum: Errors during model validation and/or estimation.
Topic: Unexpected numeric error while estimating eMDC2 model
Replies: 5
Views: 36180

Re: Unexpected numeric error while estimating eMDC2 model

Hi, The eMDC model always assumes an outside good, it is part of the model. However, one of the interesting characteristics of the model is that it allows you to leave the consumed amount of the outside good (or equivalently the budget) undefined. Therefore, you still need to define the utility of t...
by dpalma
09 Oct 2023, 18:01
Forum: Model estimation
Topic: How to change the setting of delta matrix (for complementarity)
Replies: 7
Views: 51286

Re: How to change the setting of delta matrix (for complementarity)

Hi, Sorry for the delayed response. A few points before getting to your actual question. The fact that a model passes the "Testing the influence of parameters" stage does not imply that the model is correctly identified, as this is a necessary but not sufficient condition for identificatio...