Box Plots are useful tool for visualizing distributions and comparing similar groups
A box plot, also known as a box and whisker plot, shows the distribution and spread of data expressed in quartiles. Hovering over the box plot shows 7 statistical quantities that can help describe the data.
- Max: This is the highest value in the group. This value includes outliers.
- Upper fence: This boundary is set at 1.5 * IQR. The IQR (inter-quartile range) is defined as Q3 - Q1.
- Q3: Third quartile (75%), or the median of the upper half of the group.
- Median: The second quartile (50%), or the middle value of the group.
- Q1: First quartile (25%, or the median of the bottom half of the group.
- Lower fence: This boundary is set at 1.5 * IQR. The IQR (inter-quartile range) is defined as Q3 - Q1.
- Min: This is the lowest value in the group. This value includes outliers.
Selecting the X axis
The groups on the X axis are determined in the "Groups & Categories" section on the charting panel. In the example above, "SLITTER_1" through "SLITTER_5" are values of the metadata field "Cathode Electrode Manufacturing Equipment ID".
Another option is to group by a device attribute. For example, choose this option to group cells by Lot ID, build date, or cathode mass.
Another option is to group by analysis group. This forms groups based on the selection of tests into each analysis group, and is useful for forming arbitrary selections based on test names, tags, or ad-hoc analysis.
Selecting the Y axis
The Y axis is determined by choosing a data type, a metric, and the cycle number. In this example, the box plot will visualize the Per-Cycle Metric of Discharge Capacity at Cycle 1.
Formatting box plots
Box plots can be formatted by clicking on 'Formatting' in the top right of the charting panel. In "Trace Formatting", Box-plot specific options are under "Box and Points Display". The available choices are:
Horizontal Display: This option orients the box plots from left to right, instead of top to bottom.
Box Body Opacity: This controls the transparency of the box body.
Box and Whisker Line Opacity: This controls the transparency of the whisker line.
Box and Whisker Line Width: This controls the width of the lines in the plot.
Whisker Span: This controls the horizontal width of the upper and lower fences.
Point Body Size: This controls the size of the points that lie outside the fences.
Point Body Opacity: This controls the transparency of the points. To make the points completely transparent, lower the opacity to 0%.
Point Outline Opacity: This controls the transparency of the outline of the points. To make it completely transparent, lower the opacity to 0%.
Point Outline Width: This controls the outline width of the points.
Point Jitter: This controls the 'noise' or spread of the points.
Point Position: This controls whether the points are to the left, in line with, or to the right of the box plot body.
To change the color of box plots, choose "Trace Color and Display". This menu also has a selection to toggle the display of outlier points on and off.