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 998 matches
- 29 Jan 2024, 16:08
- Forum: Feature requests
- Topic: A data contain too many observations for each person even workInLogs=TRUE
- Replies: 3
- Views: 923
Re: A data contain too many observations for each person even workInLogs=TRUE
Hi this is an extreme case. Do you have that large a number of choices for each person in the data or just for one person (in which case they will dominate the data). If you're not going to run a model with random parameters, then you may consider treating the data as if it came from separate people...
- 20 Jan 2024, 00:11
- Forum: Post-estimation analysis/use of results
- Topic: Marginal Effect or Elasticity
- Replies: 1
- Views: 591
Re: Marginal Effect or Elasticity
Hi
an elasticity relates to a percent change, so only applies for continuous explanatory variables. You could look at the predicted demand at the different levels of your categorical variables
Stephane
an elasticity relates to a percent change, so only applies for continuous explanatory variables. You could look at the predicted demand at the different levels of your categorical variables
Stephane
- 19 Jan 2024, 01:34
- Forum: Feature requests
- Topic: Any plan for a port in Julia?
- Replies: 2
- Views: 1112
Re: Any plan for a port in Julia?
Hi
sorry, we don't have resources for that
Stephane
sorry, we don't have resources for that
Stephane
- 19 Jan 2024, 01:33
- Forum: Errors during model validation and/or estimation.
- Topic: "Estimation failed. No covariance matrix to compute" with Box-Cox Utility
- Replies: 1
- Views: 1261
Re: "Estimation failed. No covariance matrix to compute" with Box-Cox Utility
Gabriel apologies for the slow reply, David and I have been away. It doesn't really make sense to me to apply a box-cox transform to the entire utility. The normal thing would be to apply it to the explanatory variables prior to multiplication by the associated beta. We would typically expect lambda...
- 19 Jan 2024, 01:28
- Forum: Post-estimation analysis/use of results
- Topic: Package for export of results into tables
- Replies: 1
- Views: 462
Re: Package for export of results into tables
Hi
apologies for the slow reply, David and I have been away.
I don't know of a package per se. But you could try the apollo_combineResults function which produces a csv that includes an overview of the results
Stephane
apologies for the slow reply, David and I have been away.
I don't know of a package per se. But you could try the apollo_combineResults function which produces a csv that includes an overview of the results
Stephane
- 19 Jan 2024, 01:27
- Forum: Estimation results
- Topic: When to use robust standard errors and "normal" standard errors?
- Replies: 1
- Views: 533
Re: When to use robust standard errors and "normal" standard errors?
Pea
apologies for the slow reply, David and I have been away.
I always use robust standard errors. They make far fewer assumptions than classical ones.
Stephane
apologies for the slow reply, David and I have been away.
I always use robust standard errors. They make far fewer assumptions than classical ones.
Stephane
- 19 Jan 2024, 01:25
- Forum: Estimation results
- Topic: Unreasonable estimate for price and other attributes
- Replies: 5
- Views: 881
Re: Unreasonable estimate for price and other attributes
Hi
apologies for the slow reply, David and I have been away.
There is nothing wrong with your code at face value. Can you tell us more about the experiment? You might want to test the model with all attributes treated as categorical as opposed to linear.
Stephane
apologies for the slow reply, David and I have been away.
There is nothing wrong with your code at face value. Can you tell us more about the experiment? You might want to test the model with all attributes treated as categorical as opposed to linear.
Stephane
- 19 Jan 2024, 01:21
- Forum: Errors during model validation and/or estimation.
- Topic: Parameter b does not influence the log-likelihood of model
- Replies: 1
- Views: 1140
Re: Parameter b does not influence the log-likelihood of model
Hi
apologies for the slow reply, David and I have been away.
Your model is not identified. You have included
in all utility functions. Only differences in utility matter, so this term would drop out
Stephane
apologies for the slow reply, David and I have been away.
Your model is not identified. You have included
Code: Select all
+ b_revisit[[s]] * (times==1) Stephane
- 19 Jan 2024, 01:13
- Forum: Examples (existing and requests for new ones)
- Topic: Three-levels NL model, utility equation
- Replies: 1
- Views: 643
Re: Three-levels NL model, utility equation
Kathy
apologies for the slow reply, David and I have been away.
There is no specific provision in Apollo for nest-specific utilities, but you can add those parts into the utilities for each of the alternatives in the nest
Stephane
apologies for the slow reply, David and I have been away.
There is no specific provision in Apollo for nest-specific utilities, but you can add those parts into the utilities for each of the alternatives in the nest
Stephane
- 08 Dec 2023, 10:41
- Forum: Estimation results
- Topic: Differences in Estimates in WTP space and preference space
- Replies: 5
- Views: 82007
Re: Differences in Estimates in WTP space and preference space
You mean ra and rl? Why don't you also include those in the WTP space spec?
in relation to calculating wtp in preference space, you would just take the ratios of the random parameters
in relation to calculating wtp in preference space, you would just take the ratios of the random parameters