create_lagged_cov function

Create lagged choice covariates

This function creates lagged choice covariates from the data.frame

choice_data, which is assumed to be sorted by the choice occasions.

create_lagged_cov(choice_data, column, k = 1, id = "id")

Arguments

• choice_data: A data.frame of choice data in wide format, i.e. each row represents one choice occasion.
• column: A character, the column name in choice_data, i.e. the covariate name. Can be a vector.
• k: A positive number, the number of lags (in units of observations), see the details. Can be a vector. The default is k = 1.
• id: A character, the name of the column in choice_data that contains unique identifier for each decision maker. The default is "id".

Returns

The input choice_data with the additional columns named column.k for each element column and each number k

containing the lagged covariates.

Details

Say that choice_data contains the column column. Then, the function call

create_lagged_cov(choice_data, column, k, id)

returns the input choice_data which includes a new column named column.k. This column contains for each decider (based on id) and each choice occasion the covariate faced before k choice occasions. If this data point is not available, it is set to NA. In particular, the first k values of column.k will be NA (initial condition problem).