ApolloChoiceModelling forum

Hi,

I am not sure I got all the details right of what you want to do, but let’s start with the following case and take it from there.

Let’s say your choice model has 5 alternatives: working 1, 2, 3, 4, or 5 days a week. And you only have two explanatory variables: income_j (the income that the ...

Hi Johnathan,

As Stephane mentioned, we thought about making apollo_searchStart, apollo_bootstrap, and apollo_outOfSample perform parallel estimation at the model level before, as opposed to using parallel estimation within each model. However, we did not do it because sharing the pre-processing ...

Hi Gaby,

The code looks good to me. So I think from a theoretical perspective you are good. From a practical perspective, the formulation may be difficult to estimate.

Personally, I do not recall ever estimating a model with mediating effects for (interaction between) latent variables, so I do not ...

Hi Katya,

If these are warnings you get after estimation, I would not worry about them. During the optimisation process the algorithm may try invalid parameter values (e.g. a negative g_first < 0). These will generate the warning, but the optimiser will be smart enough to try another value (i.e. a ...

Hi,

The function apollo_mdcev has an option called rawPrediction you can use to simulate choices from an MDCEV model.

The way the forecasting of MDCEV works, is that -for each individual- it simulates data from the model several times (100 times by default), and then averages the forecasting ...

Hi,

I am very surprised to hear you got a negative estimate for sigma in MDCEV (or eMDC). The likelihoods of these models would break down for negative values of sigma. If you can, please share your code and data with me through email. You can write to David.Palma[at]uab.cat

Best wishes,
David

Hi Mohammed,

The eMDC is a model with several moving parts. In particular, the presence of complementarity/substitution parameters can make estimation tricky, as for certain combinations of values they can lead to decreasing marginal utilities. So it is always a good idea to first find a good ...

Hi,

You are correct about cont_sd and disc_sd, but not expe_sd.

Before defining them it is important to understand how the forecast of MDCEV is calculated. The forecast is based on simulation. For each row in your data, a draw for each good or alternative is drawn, then the consumer utility ...

Hi Chris,

We discussed this through email, but thought it was good to answer this in the forum as well so that others can benefit too.

In the case where several of your inside goods are always consumed, it might be better to consider all of them as outside goods. This means that your model will ...

Hi,

The forecast contains the following columns (in the following order):

Expected consumption of outside, then all inside goods.
The s.d. of the previous values
Expected probability of consuming (i.e. non-zero consumption) of each good
The s.d. of the previous values.


Thanks for noticing ...