Adding Mean Values to a Scatterplot

These directions assume you’ve already made a scatterplot with categories along the xaxis (go here for general directions).

The following example is based on the butterfly data set which you can find here.

Once you make and format your scatterplot, it should something look like this (for tips on formatting your graph, go here):

To add mean values to a scatterplot, you need to setup two new columns in your data sheet, the first with the numbers representing your categories (in this case, 1, 2, and 3); the second with the corresponding mean values. You can calculate mean values using a calculator, formulas in Excel, or get them from statistical output from a tTest or ANOVA.

The two new columns in your spreadsheet should look like this:

To add the mean values to your graph, right click within the graph and click Select Data. You should see a window that looks like this:

Click Add, then type “mean values” for your Series name.

Click in the Series X values box, and drag down your column of category values.

Click in the Series Y values box (if you see “={1}”, delete it), then drag down your
column with your mean values.
Click OK. You should now see your mean values displayed on your graph something like this:

In order to change the symbols on your graph, double click them so that you see a window like this:

The most useful settings to change are Marker Options, Marker Fill, and Marker Line Color.

If you’ll be printing out your graph, consider using colors that will work well when shown in black and white (or just use black or gray symbols).

Here’s an example of symbols that will work for black and white printouts:

It’s important that you either include a figure legend that shows what your symbols mean (as shown above), or explain your symbols in your figure description (as shown below).
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