Effectively showing closely spaced data points

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Thu, 01/29/2015 - 08:23 am

I have data that very closely overlap and are difficult to see individually -- example of what looks like two points in middle of attached graph. What is an effective way of showing this data that is otherwise covered by the other points? I understand this is not related to Igor pro per se but I'd appreciate your feedback.
There's a few possibilities: Reduce marker size, put any other lines etc behind the markers, zoom the region (as suggested above). Igor doesn't do opacity at present but you can export to Illustrator and change the opacity so that only markers that overlap are at 100%. Other possibilities if you have lots of data points: use dots in Igor, or make a bivariate histogram do show the density of points. Finally, for categories you can spread the points about x using scatter dot plot.

January 29, 2015 at 01:21 pm - Permalink