20 March 2017

Different View of Shared cM Project Data

A while ago Blaine T. Bettinger gathered data (and is still collecting more data) for the Shared cM Project which he published. His charts fit on one page and shows the estimated average, and more importantly, actual minimum and maximum amount of shared cM reported between two test-takers with a known relationships.

I love Blaine's chart because all of the data fits on one page, but for visual learners the overlap in the minimum and maximum numbers is easier to see in a bar chart format. Since Blaine published his data under a Creative Commons "CC 4.0 Attribution License" others can adapt the data and publish changes under the same license.

So I reformatted Blaine's data in a bar chart format. One complete chart is available which should be printed on 11x17 paper in landscape format to be easily readable. The chart is also split into four parts with some overlapping relationships to allow the data to be printed in a more readable format in four pieces. To me, this is easier to show someone so they can see that sharing, for example, 100 cM, could fall into any of nine relationships shown on the chart. And the chart does not even include all of the potential double, half, and removed possibilities for cousins. I hope these are as useful for other researchers as they are for me.

Click the links below to access full size images.

To cite this blog post:
Debbie Parker Wayne, "Different View of Shared cM Project Data," Deb's Delvings, 20 March 2017 (http://debsdelvings.blogspot.com/ : accessed [date]).

© 2017, Debbie Parker Wayne, Certified Genealogist®, All Rights Reserved


  1. A helpful companion reference to Blaine's chart! Thank you!

    1. Thanks, Michelle. I hope you find it useful to share with others.

  2. Simple, helpful, visualization tool. It's Great!