Strip charts are a way of visualising the distribution of data by plotting the data points along an axis. They’re particularly useful for comparing multiple data distributions.
Essentially each distribution is plotted along a common Y-axis and has a discrete region of the X-axis to separate the series from each other. To make it easier to distinguish points from each other, they have a random “jitter” added to the X co-ordinate of each point. QuickChart adds this jitter automatically; you can specify the desired amount in the Settings dialog box (see Settings below).
To make a strip chart, simply select the series for inclusion and press the Strip Chart button, which is in the “Distribution Charts” group on the Excel ribbon.
The chart created with a single click retains a link to the Y-values of the data, but the X-values are fixed numbers, stored in the series formula of the chart, as illustrated below.
For most purposes, this is fine, but there may be occasions when you want to have more control over the X-values as well. In this case, you may want to use the “=QC.STRIP(…)” formula.
There are just four parameters for this formula: the source data (including series titles), the width of the jitter, whether or not you want the jitter to be proportional to the number of points, and “TRUE” if the chart is to be horizontal and “FALSE” if it is to be vertical.
Like most of the other QuickChart formulae, this is an array formula, so you must use “Ctrl-Shift-Enter” when you complete it, and select the full range required (although the most recent versions of Excel provide much better support for array formulae). More details on array formulae here.
Once you’ve entered the formula, just select a cell in the formula range and press the “Strip Chart” button on the ribbon (as you do to make the single-click version) or right-click and the “Make Strip Chart” option should be at the top of the context menu.
Full examples of the strip charts and formulae are in the example workbook provided with the QuickChart download.
- Vertical / Horizontal – sets the orientation of the chart for both single-click and formula-based charts.
- Maximum Jitter – how wide should the distribution of the points be? This can be set up to a maximum of 1.
- Proportional Jitter – makes the amount of jitter vary with the number of points in a particular section of the chart. This means that points in sparse regions are closer to the centre of the strip, and points in dense regions vary more widely.
- Semi-Transparent Markers – If you are plotting many points in a series, making them semi-transparent makes it clearer that some points lie beneath other points.
- Show Legend – This usually isn’t required on a strip chart but you can choose to have the legend visible.