DNA Match Analyzer was created to assist in figuring out where a person who took a DNA test fits into a family tree. The test taker is generally an adoptee looking for birth parents.
DNA Match Analyzer takes as input a Gedcom file annotated with the strength of the DNA connection that the test taker shares with people in the tree, and produces as output a report that shows relationships between the test taker and people in the tree. See the detailed instructions for more information.
If you have a hypothesis about where the tester might fit into a tree, DNA Match Analyzer can help you test that hypothesis by producing a report for how well that location in the tree fits with the DNA provided. To use this feature, create a fake person at that location in the tree, add the word "analyze" to the suffix of data attached to that person and submit the Gedcom. If there is already a suffix, you can separate the parts with semi-colons (";"). See the detailed instructions for more information.
DNA Match Analyzer does not do any magic. It attempts to deduce where a tester might fit into a tree based on shard matches by creating synthetic people and doing math. If the matches that are in the tree don't provide enough data for good conclusions to be drawn, it cannot draw good conclusions, and the output may not be very helpful.
The output is broken into a number of sections. The first section is simply some a text overview of what has been done, the second details the matches, and the third contains the match summary reports. This sample report is generated from my matches which share < 600cM (the names have been changed to protect identities). You can download the Gedcom it was generated from if you would look to see the input (or try it yourself).
The output begins with a text summary, and then contains a summary of the inputs:
It then lists the matches found embedded in the tree. It is important to double check that all the matches you expected to be in the input are there:
People that are in the input tree are referred to as real people. In order to help consider “all possibilities”, the program creates several different kinds of synthetic people. Unless you understand how they are created and named, you will not be able to understand the report. The first step the program takes is to fill in the tree by ensuring at all real people have two parents, a full sibling and a half sibling for each parent.
To do this, the following people are created:
The program computes a score for every person it analyzes. The score is based on whether the number of cMs shared with the match fit within the 95 percentile values from the Shared cM project's table of DNA matches. The score is the total number of cMs that were within the expected range from the minus the number of cMs that were not within the expected range. More precisely, the score is computed as:
Score is initially set to 0. For every match in the tree:
Here is a sample of a single analysis from the program:
Because DNA transfer is random, there is no "sure thing" in interpreting the results, and interpreting less obvious results is more of art than science.
In the sample above, the fact that two high matches (504 and 357) cM do not fit, it is fairly obvious that the person who took the test is not the "Grandchild of Diane Martinez and Darren Ferguson".
You must add your DNA matches to your family tree, export the tree and upload it to DNA Match Analyzer. See the Detailed Instructions page for information on getting started.