Preference & WTP Space Utility Parameterizations

The {logitr} package requires that data be structured in a data.frame and arranged in a "long" format [@Wickham2014] where each row contains data on a single alternative from a choice observation. The choice observations do not have to be symmetric, meaning they can have a "ragged" structure where different choice observations have different numbers of alternatives. The data must also include variables for each of the following:

Outcome: A dummy-coded variable that identifies which alternative was chosen (1 is chosen, 0 is not chosen). Only one alternative should have a 1 per choice observation.
Observation ID: A sequence of repeated numbers that identifies each unique choice observation. For example, if the first three choice observations had 2 alternatives each, then the first 6 rows of the obsID variable would be 1, 1, 2, 2, 3, 3.
Covariates: Other variables that will be used as model covariates.