ggplot2 Bar Graph Error Bars

library(ggplot2)
library(dplyr)

set.seed(2018-03-23)

# Generate exmaple data

data <- data_frame(Condition = c(rep("Control", 50), rep("Treatment", 75)),
                   Status = c(rbinom(50, 1, .5), rbinom(75, 1, .35)))

data %>% 
  slice(c(1:5 , 51:55))

## # A tibble: 10 x 2
##    Condition Status
##    <chr>      <int>
##  1 Control        1
##  2 Control        1
##  3 Control        1
##  4 Control        1
##  5 Control        0
##  6 Treatment      1
##  7 Treatment      1
##  8 Treatment      0
##  9 Treatment      1
## 10 Treatment      0

# Visualize binary proportions in each group

ggplot(data, aes(Status)) +
  geom_bar(aes(fill = Condition))

data_avgs <- data %>%
  group_by(Condition) %>% 
  summarize(Avg = mean(Status),
            SD = sd(Status),
            N = n()) %>% 
  ungroup() %>% 
  mutate(L_CI = Avg - 1.96 * sqrt(Avg * (1 - Avg) / N)) %>% 
  mutate(U_CI = Avg + 1.96 * sqrt(Avg * (1 - Avg) / N))

data_avgs

## # A tibble: 2 x 6
##   Condition   Avg    SD     N  L_CI  U_CI
##   <chr>     <dbl> <dbl> <int> <dbl> <dbl>
## 1 Control   0.560 0.501    50 0.422 0.698
## 2 Treatment 0.320 0.470    75 0.214 0.426

# Visualize average proportion

ggplot(data_avgs, aes(Condition, Avg)) +
  geom_col(fill = "royalblue1") + 
  geom_errorbar(aes(ymin = L_CI, ymax = U_CI), width = .25)

ggplot2 Bar Graph Error Bars

Sean Kross

2018-03-23