Plotting normal curves

library(tidyverse)

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theme_set(theme_bw())

Plotting normal curves

Normal curve with base graphics

curve(dnorm(x, mean = 0, sd = 1), -4, 4)

Normal curve with ggplot

ggplot(data = data.frame(x = c(-4, 4)), aes(x = x)) +
  stat_function(fun = dnorm, args = list(mean = 0, sd = 1)) +
  theme(axis.title.y=element_blank()) +
  scale_y_continuous(breaks = NULL)

Shade the regions from -1.96 to +1.96

x <- seq(from = -4, to = 4, by = .01)
normal_df <- data.frame(x = x, y = dnorm(x, mean = 0, sd = 1))

ggplot(data = data.frame(x = c(-4, 4)), aes(x = x)) +
  geom_area(data = filter(normal_df, x >= -1.96 & x <= 1.96), aes(x = x, y = y), fill = "lightblue") +
  stat_function(fun = dnorm, args = list(mean = 0, sd = 1)) +
  theme(axis.title.y=element_blank()) +
  scale_y_continuous(breaks = NULL)