Adding asterisks for significance in bar graphs

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Wed, 11/13/2013 - 08:08 am

Hello,

I have a plot of 3 bar graphs(mean +- sem) and would like to add asterisks above the graphs and lines between the graphs whose differences in mean are significant(as is commonly done). Would I have to do this manually by drawing them in or is there a built in igor function? It would be nice if there was a way to perform a one-way Anova and generate the graph with the relevant means,measures of spread and add the asterisks denoting significance automatically although I have not found anything in the manual to indicate this is possible in one go.

Thanks for your time
I'll let someone else address the ANOVA.

You can add the asterisks as a second copy of your trace using Text Markers. To read more about text markers, copy this command, paste it into Igor's command line and hit Enter:

DisplayHelpTopic "Text Markers"

Prepare a text wave with asterisks in the appropriate rows corresponding to the significant bars, and empty rows for the non-significant bars. In the Text Marker dialog, select that text wave as the source of the marker text. You will need to set the Y offset to a pleasing value.

If the bar graph is a category plot, you will need to set the grouping mode for the original bar trace to "Keep with Next". To do so, double-click the bars to bring up the Modify Trace Appearance dialog. Select the first trace (which should be your original bar trace) and select Keep with Next from the Grouping menu.

John Weeks
WaveMetrics, Inc.
support@wavemetrics.com

November 13, 2013 at 09:25 am - Permalink

epiphenom wrote:
It would be nice if there was a way to perform a one-way Anova


To find out how to perform ANOVA execute:
DisplayHelpTopic "StatsANOVA1Test"

You may also find it helpful to try the ANOVA1 Demo experiment under File Menu->Example Experiments->Statistics->ANOVA1 Demo.

A.G.
WaveMetrics, Inc.

November 13, 2013 at 10:10 am - Permalink