faux (version 1.2.1)

contr_code_treatment: Treatment code a factor

Description

Treatment coding sets the mean of the reference level (base) as the intercept. Each contrast compares one level with the reference level.

Usage

contr_code_treatment(fct, levels = NULL, base = 1)

Value

the factor with contrasts set

Arguments

fct

the factor to contrast code (or a vector)

levels

the levels of the factor in order

base

the index of the level to use as baseline

Examples

df <- sim_design(between = list(pet = c("cat", "dog")), 
                 mu = c(10, 20), plot = FALSE)
df$pet <- contr_code_treatment(df$pet)
lm(y ~ pet, df) %>% broom::tidy()

df <- sim_design(between = list(pet = c("cat", "dog", "ferret")), 
                 mu = c(2, 4, 9), empirical = TRUE, plot = FALSE)
                 
df$pet <- contr_code_treatment(df$pet)
lm(y ~ pet, df) %>% broom::tidy()

df$pet <- contr_code_treatment(df$pet, base = 2)
lm(y ~ pet, df) %>% broom::tidy()

df$pet <- contr_code_treatment(df$pet, base = "ferret")
lm(y ~ pet, df) %>% broom::tidy()