plot_magnitude function

Plot the mean or median for a continuous variable

plot_magnitude creates a ggplot2 plot suitable for visualizing the results of a study with one group and one or more continuous outcome variables. It can highlight either the mean or median of each outcome variable. This function can be passed an esci_estimate object generated by estimate_magnitude()

plot_magnitude(
  estimate,
  effect_size = c("mean", "median"),
  data_layout = c("random", "swarm", "none"),
  data_spread = 0.25,
  error_layout = c("halfeye", "eye", "gradient", "none"),
  error_scale = 0.3,
  error_nudge = 0.35,
  error_normalize = c("groups", "all", "panels"),
  rope = c(NA, NA),
  ggtheme = NULL
)

Arguments

• estimate: * An esci_estimate object generated by estimate_magnitude()
• effect_size: * Optional; One of 'mean' (default) or 'median'; specifies which measure of central tendency to highlight; note medians are only available if the esci_estimate object was generated from raw data
• data_layout: * Optional; One of 'random' (default), 'swarm', or 'none' for how raw data (if available) will be displayed
• data_spread: * Optional real number > 0 specifying width raw data (if available) should take on the graph; default is 0.25; default spacing between two groups on the graph is 1
• error_layout: * Optional; One of 'halfeye', 'eye', 'gradient' or 'none' for how expected sampling error of the measure of central tendency should be displayed. Currently, only applies if 'mean' is selected as measure of central tendency
• error_scale: * Optional real number > 0 specifying width of the expected sampling error visualization; default is 0.3
• error_nudge: * Optional amount by which error distribution should be offset; default is 0.35
• error_normalize: * Optional; One of 'groups' (default), 'all', or 'panels' specifying how width of expected sampling error distributions should be calculated.
• rope: * Optional two-item vector specifying a region of practical equivalence (ROPE) to be highlighted on the plot. For a point null hypothesis, pass the same value (e.g. c(0, 0) to test a point null of exactly 0); for an interval null pass ascending values (e.g. c(-1, 1))
• ggtheme: * Optional ggplot2 theme object to control overall styling; defaults to ggplot2::theme_classic()

Returns

Returns a ggplot object

Details

This function was developed primarily for student use within jamovi when learning along with the text book Introduction to the New Statistics, 2nd edition (Cumming & Calin-Jageman, 2024).

Expect breaking changes as this function is improved for general use. Work still do be done includes:

• Revise to avoid deprecated ggplot features
• Revise for consistent ability to control aesthetics and consistent layer names

Examples

# From raw data
data("data_penlaptop1")

estimate_from_raw <- esci::estimate_magnitude(
  data = data_penlaptop1[data_penlaptop1$condition == "Pen", ],
    outcome_variable = transcription
)

# To visualize the estimate
myplot_from_raw <- esci::plot_magnitude(
  estimate_from_raw,
  effect_size = "median"
)

# From summary data
mymean <- 24.5
mysd <- 3.65
myn <- 40

estimate_from_summary <- esci::estimate_magnitude(
  mean = mymean,
  sd = mysd,
  n = myn
)

# To visualize the estimate
myplot_from_summary <- esci::plot_magnitude(
  estimate_from_summary,
  effect_size = "mean"
)