Example of models with continuous and categorical coding

irine.R

## Load packages
library(rio)
library(tidyverse)
library(gtsummary) ## optional

### Read the data
dat <- rio::import("Irine_Data.sav")

summary(dat$Retrospective_)
summary(dat$Party)

dat$Retrospective_cont <- dat$Retrospective_
## Estimate a model with retrospective as a continuous variable
mod_a <- glm(Party ~ Retrospective_cont + Higher_Education + Gender,
           data = dat,
           family = binomial(link = logit))

## Estimate a model with retrospective as a categorical variable
## where "Same" is the baseline
                                        #
## First, recode
dat$Retrospective_cat <- dplyr::recode(dat$Retrospective_,
                                       `-1` = "Worse",
                                       `0` = "Same",
                                       `1` = "Better")
dat$Retrospective_cat <- factor(dat$Retrospective_cat)

### Set 'same' to be the reference category
dat$Retrospective_cat <- relevel(dat$Retrospective_cat,
                                 "Same")


## Now estimate a model
mod_b <- glm(Party ~ Retrospective_cat + Higher_Education + Gender,
             data = dat,
             family = binomial(link = logit))

## Optionally, display the results in a pretty table
cm <- c('(Intercept)' = '(Intercept)',
        'Retrospective_cont' = 'Econ evals (retrospective; continuous)',
        'Retrospective_catBetter' = 'Retrospective econ evals: better (compared to same)',
        'Retrospective_catWorse' = 'Retrospective econ evals: worse (compared to same)',
        'Higher_Education' = 'College graduate',
        'Gender' = 'Female voter')

gtsummary(list(mod_a, mod_b), coef_map = cm,
          filename = "table.html")