Distinguishing groups in a scatterplot in Excel
Suppose we wish to look graphically at the relationship of semantic closeness (as measured by euclidean distance) to priming (milliseconds) for different types of words. We can plot all three of these variables on one chart. We can do this by producing a scatterplot of euclidean distance against priming with the word types signified by different colours and shapes. The rest of this note illustrates how to produce such a plot in EXCEL although this option should be available in most other stats packages. Just look out for their scatterplot option.
Let us suppose that we have three columns of data in our EXCEL spreadsheet. One column for each of the two continuous measures euclidean distance (ED) and priming (P) with the other showing categorical word type (WT). Let us suppose we are interested in three word types: animals, household objects and manmade objects.
- The first thing we need to do is to sort ED and P by WT. To do this go to data sort and choose WT as the column of data to sort by.
- Now click on the chart wizard and choose XY (scatter) and the topmost chart (the one with a mix of shapes and colours on it) should be highlighted. Click on this and then click on the series tab. Series 1 should be highlighted in the series window. For us this represents the first word type.
- We can click on the add button and series 2 appears; click on add again and series 3 joins the list. Each series will represent a different word type.
- Now let’s go back to series 1 and click on the X values window. This will represent the values of ED for animals. Go to the spreadsheet and click and drag to highlight the ED values for animals. These row numbers for animals should immediately appear in the X values window.
- Now, click on the Y values window and repeat for P. Again the row numbers for animals will appear in that window. You have entered the data for animals. Now repeat for series 2 and series 3 inputting the ED and P values for household and manmade objects.
You can then move on and make any other edits (e.g. axis labels) before coming out of the wizard after clicking finish. You can change the marker shapes of each word type by clicking on a shape in the outputted plot, clicking the pattern tab and choosing custom Marker.