How to chart variance on Datastream Created by Lara Skelly, for the University of Cape Town Libraries Updated August 2010

The question: How to graph the variance of the Dow Jones Industrial Index with the variance of the JSE All Share Index on the same graph?

Open up Datastream, and select the Multiple Series / Flexible Chart from the Analysis section.

This opens up the basket where you can add the different series.

Choose the Expression Builder icon. It looks like a little lightning bolt with two round brackets.

This window will pop up.

Click on Tools and select Function.

This window will pop up. Select Standard deviation [period] [SDN#]

The standard deviation will then be entered into the Expression Builder. Click on the 50D which stands for the period.

This window will pop-up.

Change it to 1 Year (I don’t know why, but the Datastream guys did that in the example I had).

You will then see the 1Y in the Expression Builder. Next, select the cell between the SDN# and 1Y. You will notice that Find will no longer be grayed out. Click there. 2 1

This window will pop up. Click on the orange Find Series.

The familiar search screen appears. Search for the first series (JSE All Share Index)

You will then see it added. Click OK.

The series will then appear in the Expression Builder.

Give the expression a title, and click Save.

You will then see the expression you created in the Flexible Chart basket.

To add the second series (Dow Jones Industrial), select Add New Entries Here and click on the Select from a list button (it looks like f with a little x as a subscript) 2 1

This window will pop up. You should see your saved expression at the bottom. Select it, and click OK.

You will then see it in the Flexible Chart basket. Notice that it only adds the Expression, not the series. This is then selected in the usual way. Click on the orange Find Series button, and search. 2 1

Once you have found your series, you will see it in the Flexible Chart basket. Click Run Now! 2 1

You will see your graph, which you can then export.

As another example, this shows the Variance of the Dow Jones Industrial Index charted with the Total Returns Index.

Need more help? Ask a librarian. or Picture by Carlos Porto (Flickr)