The autosomal tests we do for genealogy examine more than 500,000 SNPs (individual units) of DNA. That’s a lot of data! Have you ever wondered how accurate the results are?
I’m not referring to how precise the ethnicity estimates are or how reliable the relationship predictions are; those are interpretations of the test results. I’m referring to something more fundamental: the raw data itself. After all, if the raw data are inaccurate, the downstream analyses could be affected, as well.
In fact, I was inspired to do this survey because I came across a case where a high error rate in the raw data led to very unusual results, so unusual that another genealogist had misidentified an adoptee’s birth father.
One estimate of the error rate in this type of test is the “no-call” rate. The no-call rate is the percentage of SNPs without a reported value. No-call rates can range from a fraction of one percent to five percent or more.
GEDmatch has a “Diagnostic Utility” tool that can quickly tell you the no-call rate. To use it, log into your account at GEDmatch and click on the tool as shown in the screenshot.
Once you’ve run the tool, please answer the Error Rate Survey to crowd-source detailed information about the no-call rates at the testing companies. You can answer the survey multiple times, once per kit.