mean_plot: Mean plot with error bars

In Rkabacoff/qacBase: Functions to Facilitate Exploratory Data Analysis

Mean plot with error bars

Description

Plots group means with error bars. Error bars can be standard deviations, standard errors, or confidence intervals. Optionally, plots can be based on robust statistics.

Usage

mean_plot(
  data,
  y,
  x,
  by,
  pointsize = 2,
  dodge = 0.2,
  lines = TRUE,
  width = 0.2,
  error_type = c("se", "sd", "ci"),
  percent = 0.95,
  robust = FALSE
)

Arguments

data	a data frame.
y	a numeric response variable.
x	a categorical explanatory variable.
by	a second categorical explanatory variable (optional).
pointsize	numeric. Point size (default = 2).
dodge	numeric. If a by variable is included, points and error bars are dodged by this amount in order to avoid overlap (default = 0.2).
lines	logical. If TRUE, group means are connected.
width	numeric. Width of the error bars (default = 0.2). Set to 0 to produce pointranges instead of error bars.
error_type	character. Error bars represents either standard deviations (sd), standard errors of the means (se), or confidence intervals (ci). The default is the standard error.
percent	numeric. if error_type = "ci", this indicates the size of the confidence interval. The default is 0.95 or a 95 percent confidence interval for the mean.
robust	logical. If TRUE, the means, standard deviations, standard errors, and confidence intervals are based on robust statistics. See Details. The default is FALSE.

Details

Robust statistics are based on deciles, the nine values that divide the response variable into 10 equal groups (where each group contains roughly the same fraction of cases). The robust mean is the mean of these nine decile values. The robust standard deviation is the sample standard deviation of the nine decile values. The standard error and confidence interval are calculated in the normal way, but use the robust mean and standard deviation in their calculations. See Abu-Shawiesh et al (2022).

Value

a ggplot2 graph.

References

Ahmed Abu-Shawiesh, M., Sinsomboonthong, J., & Kibria, B. (2022). A modified robust confidence interval for the population mean of distributrion baed on deciles. Statistics in Transition, vol. 23 (1). pdf

Examples

mean_plot(cars74, mpg, cyl)
mean_plot(cars74, mpg, cyl, am)
mean_plot(cars74, mpg, cyl, am, 
          error_type = "ci", percent = 0.9,
          width = 0, lines = FALSE, robust = TRUE)

Rkabacoff/qacBase documentation built on June 23, 2022, 7:13 p.m.