Decode: Coded design to readable design.

In idefix: Efficient Designs for Discrete Choice Experiments

Coded design to readable design.

Description

Transforms a coded design matrix into a design containing character attribute levels, ready to be used in a survey. The frequency of each attribute level in the design is also included in the output.

Usage

Decode(
  des,
  n.alts,
  lvl.names,
  coding,
  alt.cte = NULL,
  c.lvls = NULL,
  no.choice = NULL
)

Arguments

des	A numeric matrix which represents the design matrix. Each row is a profile.
n.alts	Numeric value indicating the number of alternatives per choice set.
lvl.names	A list containing character vectors with the values of each level of each attribute.
coding	A character vector denoting the type of coding used for each attribute. See also Profiles.
alt.cte	A binary vector indicating for each alternative if an alternative specific constant is present. The default is NULL.
c.lvls	A list containing numeric vectors with the attribute levels for each continuous attribute. The default is NULL.
no.choice	An integer indicating the no choice alternative. The default is NULL.

Details

des A design matrix, this can also be a single choice set. See for example the output of Modfed or CEA.

In lvl.names, the number of character vectors in the list should equal the number of attributes in de choice set. The number of elements in each character vector should equal the number of levels for that attribute.

Valid arguments for coding are C, D and E. When using C the attribute will be treated as continuous and no coding will be applied. All possible levels of that attribute should then be specified in c.lvls. If D (dummy coding) is used contr.treatment will be applied to that attribute. The first attribute wil be used as reference level. For E (effect coding) contr.sum is applied, in this case the last attribute level is used as reference level.

If des contains columns for alternative specific constants, alt.cte should be specified. In this case, the first column(s) (equal to the number of nonzero elements in alt.cte) will be removed from des before decoding the alternatives.

Value

design	A character matrix which represents the design.
lvl.balance	A list containing the frequency of appearance of each attribute level in the design.

Examples

## Not run: 
# Example without continuous attributes.
design <- example_design 
coded <- c("D", "D", "D") # Coding.
# Levels as they should appear in survey. 
al <- list(
  c("$50", "$75", "$100"), # Levels attribute 1.
  c("2 min", "15 min", "30 min"), # Levels attribute 2.
  c("bad", "moderate", "good") # Levels attribute 3.
) 
# Decode
Decode(des = design, n.alts = 2, lvl.names = al, coding = coded) 

# Example with alternative specific constants
design <- example_design2 
coded <- c("D", "D", "D") # Coding.
# Levels as they should appear in survey. 
al <- list(
  c("$50", "$75", "$100"), # Levels attribute 1.
  c("2 min", "15 min", "30 min"), # Levels attribute 2.
  c("bad", "moderate", "good") # Levels attribute 3.
) 
# Decode
Decode(des = design, n.alts = 3, lvl.names = al, coding = coded, alt.cte = c(1, 1, 0)) 

## End(Not run)

idefix documentation built on March 28, 2022, 5:05 p.m.