CODEWITHSUNDEEP
rcombinationslogistic-regressioncategorical-datadummy-variable
Zeinab Elashidy
Zeinab Elashidy

Reputation: 11

Creating a combination of dummy variables into a single variable in a logistic regression model in R

I need to create possible combinations of 3 dummy variables into one categorical variable in a logistic regression using R. I made the combination manually just like the following:

new_variable_code variable_1 variable_2 variable_3
1 0 0 0
2 0 1 0
3 0 1 1
4 1 0 0
5 1 1 0
6 1 1 1

I excluded the other two options (0 0 1) and (1 0 1) because I do not need them, they are not represented by the data. I then used new_variable_code as a factor in the logistic regression along with other predictors.

My question is: Is there is any automated way to create the same new_variable_code? or even another econometric technique to encode the 3 dummy variables into 1 categorical variable inside a logistic regression model?

My objective: To understand which variable combination has the highest odds ratio on the outcome variable (along with other predictors explained in the same model).

Thank you

Upvotes: 1

Views: 601

Answers (2)

IRTFM
IRTFM

Reputation: 263301

I would just create a variable with paste using sep="." and make it a factor:

 newvar <- factor( paste(variable_1,    variable_2, variable_3, sep="."))

I don't think it would be a good idea to then make it a sequential vlaue, it's already an integer with levels, since that's how factors get created.

Upvotes: 1

Rory S
Rory S

Reputation: 1298

You could use pmap_dbl in the following way to recode your dummy variables to a 1-6 scale:

library(tidyverse)

# Reproducing your data
df1 <- tibble(
  variable_1 = c(0,0,0,1,1,1),
  variable_2 = c(0,1,1,0,1,1),
  variable_3 = c(0,0,1,0,0,1)
)

factorlevels <- c("000","010","011","100","110","111")

df1 <- df1 %>%
  mutate(
    new_variable_code = pmap_dbl(list(variable_1, variable_2, variable_3),
                                 ~ which(paste0(..1, ..2, ..3) == factorlevels))
  )

Output:

# A tibble: 6 x 4
  variable_1 variable_2 variable_3 new_variable_code
       <dbl>      <dbl>      <dbl>             <dbl>
1          0          0          0                 1
2          0          1          0                 2
3          0          1          1                 3
4          1          0          0                 4
5          1          1          0                 5
6          1          1          1                 6

Upvotes: 1

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