update_utility: Update the utility function

In spdesign: Designing Stated Preference Experiments

Update the utility function

Description

Updates the utility function to consider dummy coded attributes. It will expand the dummy-coding to K-1 dropping the lowest level. This is consistent with standard practice.

Usage

update_utility(x)

Arguments

x	An object of class utility

Details

The function is called prior to evaluating designs if dummy-coded attributes are present in the utility function. This is because the utility function is evaluated in the context of the design environment and must be added there

Important to note about the naming of the expanded priors and attributes: The names for the attributes will be attached with the level of the factor, whereas the prior will be named corresponding to the level, e.g., 2, 3, 4. This is simply the result of the difference between how it's extracted from the utility functions and how model.matrix creates names.

Value

An updated cleaned utility expression

spdesign documentation built on Oct. 18, 2024, 5:07 p.m.