An Overview of GEDMatch's Comparison Matrices in Multiple Kit Analysis
In GEDmatch, there is a tool called the Multiple Kit Analysis tool. And as part
of that tool, there is a function where we can look at multiple people compared
to multiple other people all at the same time. That happens through a feature called Matrices.
How to Compare DNA Matches With Matrix Tools
There are multiple ways that we can look at multiple people. Follow these steps, as shown in the video listed below.
Access your GEDmatch Tag Groups.
Select a Tag Groups
Click Visualize that group.
Once you click visualize, you have several options to compare your DNA results with others. The one we're talking about today is the Matrices tab.
Click the Matrices Tab
Select a Matrix View
To watch the GEDmatch Matrix overview, watch the video below.
There are six different matrices to choose from.
Fully Identical SNP Matrix
Fully Identical Regions Centimorgans Matrix Comparison
Each one of these comparisons has some useful information that you may want to use in your research.
Autosomal Matrix Comparison
I often leave all of the presets as the default settings. After I choose a Tag Group, I see a list of all the people in that group on the side, and it has a list of the same people along the top.
At each of these intersections of these boxes, that is the amount of DNA that those two people share.
You can see that where the two same people intersect, you have this grey box. That's going to be a diagonal all the way across your matrix because those are the same people. We're really more concerned with how that person matches somebody else.
Notice the results are color-coded based on how closely the matches are related. If the matches are parents or siblings, they will be green or even dark green. If they are first, second, or third cousins, you'll see orange and yellows.
If they're really distant, then they're going to be red. If there's no shared DNA, then
the blocks are going to be blank.
Before auto clustering, this is a tool that I would use to begin to create clusters. I would download this to a spreadsheet and then move everything around to create my own clusters. I still use this because much of this DNA data, the amount of
shared centimorgans are very valuable.
Generations Matrix Comparison
The Generations Matrix looks almost identical to the Autosomal Matrix Comparison. It is the list of people on the side, the list of people across the top, and the intersection boxes.
Instead of showing how much shared centimorgans, this matrix displays how many generations removed DNA matches are.
This is another way to help start to form genetic clusters and see how people might be related.
The X-DNA Comparison will appear very similar to the previous matrix, but this tool only shows your X-DNA matches.
In the video, I showcase the matrix of my grandfather. Because he's male, he only received one X chromosome, and that was from his mother. All of his X-DNA Comparison matches will be on his maternal side. His results had some pretty matches.
In some cases, you can determine a mother-child relationship because of how much DNA on the X chromosome two matches share. Some matches may be significant enough, 15 or more centimorgans, that you might be able to figure out the relationship depending on how far distant the Autosomal DNA shows that relationship is.
Overlap Matrix Comparison
Now I don't find the Overlap Matrix Comparison as useful. However, if you want to see how different kits may match each other and which ones are going to be the most likely to have good matches, you might use the Overlap Matrix Comparison.
The Overlap Matrix shows how many SNPs that these two kits share in common. If you want to learn more about this topic, read the post How do overlapping genes impact GEDmatch results?
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Fully Identical SNPs
The Fully Identical SNPs and Full Identical Region matrices are used primarily if you are trying to determine which kits are parent/child or which kits are the same people.
The Fully Identical SNP Comparison compares all of the Fully Identical SNPs, and what fraction of all of your SNPs are fully identical between any two people. Now while you would think when two people are different that they won't share many SNPs. Actually, most people probably have about half to two-thirds of all of their SNPs in common with any other person.
If I see nearly all of the same SNPs in common, the results are either from the same person or a twin. In the video, I actually demonstrate how the tests reveal that my fictional twin Phil has nearly the same results as me.
In contrast, my father and I have about two-thirds of our SNPs in common. This would confirm a parent-child relationship.
Fully Identical Centimorgan Matrix Comparison
This matrix compares kits that have fully identical, not just half identical, but fully identical regions. So you can quickly see which ones are siblings and which ones are the same person.
You can review your results to see how much DNA you share with your extended family members. In my case, I compared myself to my father's siblings.
What I can not see in this matrix are parent-child relationships.
Your research question will determine whether you use the Fully Identical CM
Matrix or the Fully Identical SNP Matrix
Multiple Kit Analysis is a Premium Tool
Matrices are a great way to start analyzing multiple matches at the same time. The Multiple Kit Analysis tool is a Tier One tool. So you do have to subscribe to the GEDmatch website to use it. However, the matrix options included in the Multiple Kit Analysis tool are worth having a subscription to GED match.
More Tips on Using GEDmatch
Explore the following blog posts to continue your genetic genealogy education.