plot_group_means function

Plot group means

Creates a plot of sample means and error bars by group.

plot_group_means(
  data = NULL,
  dv_name = NULL,
  iv_name = NULL,
  na.rm = TRUE,
  error_bar = "ci",
  error_bar_range = 0.95,
  error_bar_tip_width = 0.13,
  error_bar_thickness = 1,
  error_bar_caption = TRUE,
  lines_connecting_means = TRUE,
  line_colors = NULL,
  line_types = NULL,
  line_thickness = 1,
  line_size = NULL,
  dot_size = 3,
  position_dodge = 0.13,
  x_axis_title = NULL,
  y_axis_title = NULL,
  y_axis_title_vjust = 0.85,
  legend_title = NULL,
  legend_position = "right"
)

Arguments

• data: a data object (a data frame or a data.table)

• dv_name: name of the dependent variable

• iv_name: name(s) of the independent variable(s). Up to two independent variables can be supplied.

• na.rm: logical. If na.rm = TRUE, NA values in independent and dependent variables will be removed before calculating group means.

• error_bar: if error_bar = "se"; error bars will be +/-1 standard error, if error_bar = "ci" error bars will be a confidence interval; if error_bar = "pi", error bars will be a prediction interval

• error_bar_range: width of the confidence or prediction interval (default = 0.95 for 95 percent confidence or prediction interval). This argument will not apply when error_bar = "se"

• error_bar_tip_width: graphically, width of the segments at the end of error bars (default = 0.13)

• error_bar_thickness: thickness of the error bars (default = 1)

• error_bar_caption: should a caption be included to indicate the width of the error bars? (default = TRUE).

• lines_connecting_means: logical. Should lines connecting means within each group be drawn? (default = TRUE)

• line_colors: colors of the lines connecting means (default = NULL) If the second IV has two levels, then by default, line_colors = c("red", "blue")

• line_types: types of the lines connecting means (default = NULL) If the second IV has two levels, then by default, line_types = c("solid", "dashed")

• line_thickness: thickness of the lines connecting group means (default = 1)

• line_size: Deprecated. Use the 'linewidth' argument instead. (default = 1)

• dot_size: size of the dots indicating group means (default = 3)

• position_dodge: by how much should the group means and error bars be horizontally offset from each other so as not to overlap? (default = 0.13)

• x_axis_title: a character string for the x-axis title. If no input is entered, then, by default, the first value of iv_name will be used as the x-axis title.

• y_axis_title: a character string for the y-axis title. If no input is entered, then, by default, dv_name will be used as the y-axis title.

• y_axis_title_vjust: position of the y axis title (default = 0.85). By default, y_axis_title_vjust = 0.85, which means that the y axis title will be positioned at 85% of the way up from the bottom of the plot.

• legend_title: a character for the legend title. If no input is entered, then, by default, the second value of iv_name

  will be used as the legend title. If legend_title = FALSE, then the legend title will be removed.

• legend_position: position of the legend: "none", "top", "right", "bottom", "left", "none"

  (default = "right")

Returns

by default, the output will be a ggplot object. If output = "table", the output will be a data.table object.

Examples

plot_group_means(data = mtcars, dv_name = "mpg", iv_name = c("vs", "am"))
plot_group_means(
  data = mtcars, dv_name = "mpg", iv_name = c("vs", "am"),
  error_bar = "se"
)
plot_group_means(
  data = mtcars, dv_name = "mpg", iv_name = c("vs", "am"),
  error_bar = "pi", error_bar_range = 0.99
)
# set line colors and types manually
plot_group_means(
data = mtcars, dv_name = "mpg", iv_name = c("vs", "am"),
line_colors = c("green4", "purple"),
line_types = c("solid", "solid"))
# remove axis titles
plot_group_means(
data = mtcars, dv_name = "mpg", iv_name = c("vs", "am"),
x_axis_title = FALSE, y_axis_title = FALSE, legend_title = FALSE)