# 3D Box Plots - Error Bars

In this style of 3D Sequential Box Plot, the ranges of values of selected variables are plotted separately for groups of cases defined by values of a categorical (grouping) variable. The central tendency (e.g., median or mean), and range or variation statistics (e.g., min-max values, quartiles, standard errors, or standard deviations) are computed for each variable and for each group of cases and the selected values are presented as error bars.

3D Range plots differ from 3D box plots in the way in which ranges are calculated. For range plots, the dataset provides the ranges (e.g., one variable contains the minimum range values and another variable contains the maximum range values), while the ranges for box plots are calculated using the observed (raw) data (e.g., standard deviations, standard errors, or min-max value are calculated from the variable).

Graphs of Block Data. Note that when creating Box Plots with Error Bar Ranges via the Graphs of Block Data - Custom Graph options, you can create error bar ranges using the Median/Quartile/Range values or the Mean/SD/SE values. When Median/Quartile Range values are used the central tendency of each category of the variable is described in terms of the median of the values in the category (represented by the smallest box in the plot).  The spread (variability) in each category's values are represented in this plot by the quartiles (the 25th and 75th percentiles, larger box in the plot) and the minimum and maximum values of the variable (the "whiskers" in the plot).

When the Mean/SD/SE values are used the smallest box in the plot represents the mean (central tendency) of the category values, while the dispersion (variability) is represented by ± 1 times the standard error (large box) and ± 1 times the standard deviation about the mean ("whiskers").

See also, 3D Box Plots and Graphs - 3D Box Plots.