Add Dummy Variables for Piecewise Linear Models

Adds dummy variables to an scdf for calculating piecewise linear models.

Usage

add_dummy_variables(
  scdf,
  model = c("W", "H-M", "B&L-B"),
  contrast_level = c("first", "preceding"),
  contrast_slope = c("first", "preceding")
)

Arguments

scdf

A single-case data frame. See scdf() to learn about this format.

model

Model used for calculating the dummy parameters (see Huitema & McKean, 2000). Default is model = "W". Possible values are: "B&L-B", "H-M", "W", and deprecated "JW".

contrast_level

Either "first", "preceding" or a contrast matrix. If NA contrast_level is a copy of contrast.

contrast_slope

Either "first", "preceding" or a contrast matrix. If NA contrast_level is a copy of contrast.

Details

This function creates dummy variables for phase levels and phase slopes according to the specified piecewise regression model. It supports different contrast coding schemes for both level and slope contrasts.

Examples

add_dummy_variables(
 scdf = exampleABC, 
 model = "W", 
 contrast_level = "first", 
 contrast_slope = "first"
)
#> #A single-case data frame with three cases
#> 
#>  Marie: values mt phase phaseB phaseC interB interC
#>             58  0     A      0      0      0      0
#>             56  1     A      0      0      0      0
#>             60  2     A      0      0      0      0
#>             63  3     A      0      0      0      0
#>             51  4     A      0      0      0      0
#>             45  5     A      0      0      0      0
#>             44  6     A      0      0      0      0
#>             59  7     A      0      0      0      0
#>             45  8     A      0      0      0      0
#>             39  9     A      0      0      0      0
#>             83 10     B      1      0      0      0
#>             65 11     B      1      0      1      0
#>             70 12     B      1      0      2      0
#>             83 13     B      1      0      3      0
#>             70 14     B      1      0      4      0
#> # ... up to 15 more rows
#> #  two more cases