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 7 matches
- 13 Sep 2021, 16:30
- Forum: Model specification
- Topic: Correlation between alternatives
- Replies: 3
- Views: 4764
Re: Correlation between alternatives
Thank you for your advice, David. Actually, I'm trying to address the reviewer's comments, and he/she said that "It is likely that the alternatives are perceived as correlated. This should be tested in the DCM." I think it would be great if I can see that the alternatives are not significa...
- 13 Sep 2021, 16:26
- Forum: Model specification
- Topic: The distribution of random terms
- Replies: 3
- Views: 4485
Re: The distribution of random terms
Hello David, Thank you for your response. Could you please explain more about the distribution of the random terms? I followed the Apollo manual (mostly example #26), and my code is as follows: apollo_draws = list( interDrawsType="sobol", interNDraws=500 interNormDraws = c("eta_tl&quo...
- 13 Sep 2021, 01:51
- Forum: Model specification
- Topic: Correlation between alternatives
- Replies: 3
- Views: 4764
Correlation between alternatives
Hello,
I am trying to use a hybrid choice model with five alternatives. I got a question if Apollo can test the correlation between alternatives in the DCM. Would it be possible to get a test result?
Thank you very much.
I am trying to use a hybrid choice model with five alternatives. I got a question if Apollo can test the correlation between alternatives in the DCM. Would it be possible to get a test result?
Thank you very much.
- 13 Sep 2021, 01:44
- Forum: Model specification
- Topic: The distribution of random terms
- Replies: 3
- Views: 4485
The distribution of random terms
Hello, I used Apollo to develop a hybrid choice model for my study to submit a peer-reviewed journal. I got a critique on the methodology regarding the distribution of random terms in the LV model as follows: "The random terms in the latent variables are following the normal distribution N(0,1)...
- 10 May 2021, 20:21
- Forum: Post-estimation analysis/use of results
- Topic: Willingness-to-pay considering binary variable
- Replies: 5
- Views: 7000
Re: Willingness-to-pay considering binary variable
Thank you, David. I got two more questions: 1. Since the coefficient of travel cost is negative, the ratio is negative. But the value presented by Apollo is the absolute value of this ratio. Can you please clarify how this negative ratio is to be interpreted and what it means for the willingness-to-...
- 03 May 2021, 20:38
- Forum: Post-estimation analysis/use of results
- Topic: Willingness-to-pay considering binary variable
- Replies: 5
- Views: 7000
Willingness-to-pay considering binary variable
Hello, I wonder if it is appropriate to calculate WTP using binary variable and continuous variable. For example, I want to calculate the WTP of the presence of an attendant (yes = 1, no = 0). In this case, can I calculate the ratio of b_attendant and b_cost for the WTP? Your advice will be helpful ...
- 01 May 2021, 06:15
- Forum: Model specification
- Topic: Some levels in 'outcomeOrdered' do not exist in 'coding' for model component
- Replies: 8
- Views: 14979
Some levels in 'outcomeOrdered' do not exist in 'coding' for model component
I got an error message like, "Some levels in 'outcomeOrdered' do not exist in 'coding' for model component "Ind_PT01" ! My code is written as: ol_PT01 = list(outcomeOrdered=PT01, V=zeta_PT01*LV_tl, tau=c(tau_PT01_1, tau_PT01_2, tau_PT01_3, tau_PT01_4), rows=((PT01!=-99) & (Exp==1)...