plot confidence intervals for linear model with ggplot using geom_smooth

CI_lm_ggplot.R

#####################################################
# CI-s for linear model with ggplot
#####################################################

library(ggplot2)

# -------------------------------------
# Use simulated data from Mick Wu
# -------------------------------------
set.seed(1)
dat4 <- data.frame(density=rlnorm(n=600, meanlog=5,sdlog=0.5),
                   area=rep(c("forest","grass","coast"),each=200),
                   region=rep(c("north","south"),300),
                   popul=rpois(n=600,lambda=1000)^2)
dat4$density <- dat4$density + as.numeric(dat4$area)*20 + as.numeric(dat4$region)*10
dat4$density <- dat4$density * rescale(dat4$popul^2,to=c(0.25,1))

# -------------------------------------
# Plot
# -------------------------------------
ggplot(data = dat4,
       aes(x = popul,
           y = density)) +
  geom_point(shape = 21) + # add the points
  geom_smooth(method='lm') + # add the fit line and CI-s
  theme_bw() # optional; sets a black-white theme