# Choice Modeling - Diagnostic - Parameter Statistics

Produces a table of parameter statistics from a choice model.

Produces a table of parameter statistics for both Choice Modeling - Latent Class Analysis and Choice Modeling - Hierarchical Bayes outputs. With latent class analysis, this is a table containing parameter estimates and significance-testing statistics. With hierarchical Bayes, this is a table containing sample statistics of the mean and standard deviation parameters for the distribution from which individual coefficients are sampled. For more information on how to interpret this output, see this blog post, which was written for the closely-related MaxDiff analysis.

Note that with hierarchical Bayes, numeric variables are shown as scaled (this is done to improve model sampling). The prefix "Scaled" is added to numeric variable names. To descale the numeric variable coefficients, standard deviations and standard errors, multiply them by the multipliers that can be obtained by creating a new R output and typing in `choice.model$numeric.scaling` into the R CODE editor (`choice.model` needs to be replaced with the name of the choice model output) and clicking calculate. The output will contain a list of multipliers to be used for each numeric variable.

## Example

The table below shows parameter statistics from a Choice Modeling - Latent Class Analysis output:

The next table shows parameter statistics from a Choice Modeling - Hierarchical Bayes output:

## Technical details

Whenever hierarchical Bayes analysis is run with multiple classes, an attempt will be made to match class labels between chains (note that it is often not possible to match class labels). If this succeeds, or if only one chain was specified, one set of mean and standard deviation parameters will be shown for each class in the parameter statistics table. In addition, class size parameters will also be displayed. If this attempt is unsuccessful, the parameter statistics table will not be able to be shown.

## References

McLean, M. W. (2018, July 24). How to Use Hierarchical Bayes for Choice Modeling in Displayr [Blog post]. Accessed from https://www.displayr.com/how-to-hierarchical-bayes-choice-model-displayr/.

Yap, J. (2018, January 16). Checking Convergence When Using Hierarchical Bayes for MaxDiff [Blog post]. Accessed from https://www.displayr.com/convergence-hb-maxdiff/.

## How to apply this QScript

- Start typing the name of the QScript into the
**Search features and data**box in the top right of the Q window. - Click on the QScript when it appears in the
**QScripts and Rules**section of the search results.

*OR*

- Select
**Automate > Browse Online Library**. - Select this QScript from the list.

## Customizing the QScript

This QScript is written in JavaScript and can be customized by copying and modifying the JavaScript.

### Customizing QScripts in Q4.11 and more recent versions

- Start typing the name of the QScript into the
**Search features and data**box in the top right of the Q window. - Hover your mouse over the QScript when it appears in the
**QScripts and Rules**section of the search results. - Press
**Edit a Copy**(bottom-left corner of the preview). - Modify the JavaScript (see QScripts for more detail on this).
- Either:
- Run the QScript, by pressing the blue triangle button.
- Save the QScript and run it at a later time, using
**Automate > Run QScript (Macro) from File**.

### Customizing QScripts in older versions

## JavaScript

```
includeWeb("QScript R Output Functions");
main();
function main() {
// The following 2 variables contain information specific to this diagnostic.
var required_class = "FitChoice";
var output_name_suffix = "parameter.statistics";
var item = checkSelectedItemClass(required_class);
if (item == null)
return false;
var r_name = stringToRName(item.referenceName);
// The following lines contain the R code to run
var expression = "r.name <- flipChoice::ExtractParameterStats(" + r_name + ")";
return createROutput(item, expression, output_name_suffix);
}
```

## Acknowledgements

Uses the `rstan` R package.

## See also

- QScript for more general information about QScripts.
- QScript Examples Library for other examples.
- Online JavaScript Libraries for the libraries of functions that can be used when writing QScripts.
- QScript Reference for information about how QScript can manipulate the different elements of a project.
- JavaScript for information about the JavaScript programming language.
- Table JavaScript and Plot JavaScript for tools for using JavaScript to modify the appearance of tables and charts.

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