R/sleep/LR.R

In premodelling/mixed: Modelling Multilevel & Longitudinal Problems

# Title     : LR.R
# Objective : Linear Regression
# Created by: greyhypotheses
# Created on: 11/03/2022

# the data
data(sleepstudy)

# summary
summary(object = sleepstudy)


#' Linear Regression
#'
#'

# model
baseline <- lm(formula = Reaction ~ Days + Subject, data = sleepstudy)
summary(object = baseline)
best <- step(object = baseline)
summary(best)

# diagnostics
diagnostics <- sleepstudy %>%
  mutate(standardised_res = rstandard(model = best),
         fitted_value = best$fitted.values)

ggplot(data = diagnostics, mapping = aes(x = fitted_value, y = standardised_res)) +
  geom_point(alpha = 0.25) +
  geom_smooth(se = F, method = 'lm', formula = 'y ~ x') +
  theme_minimal() +
  theme(panel.grid.minor = element_blank(),
        panel.grid.major = element_line(size = 0.05),
        axis.title.x = element_text(size = 13, face = 'bold'), axis.text.x = element_text(size = 11),
        axis.title.y = element_text(size = 13, face = 'bold'), axis.text.y = element_text(size = 11)) +
  xlab(label = '\nFitted Value\n') +
  ylab(label = '\nStandardised Residual\n')