I am now finally able to evaluate the new matching system, at AncestryDNA, which uses the Timber filter to eliminate supposedly IBS segments. I was quite shocked to find a 3rd cousin 1x removed, who was a 95% confidence level match, now missing from my Mom's match list. This match is in a Circle with us and definitely isn't considered a match anymore. A cousin lost a total of 8 matches who were previously 95% confidence level matches, which no longer match at all.
Now that I have this comparison information I can evaluate the 3 companies I have experience with i.e: Family Tree DNA, AncestryDNA, and 23andMe.
- 23andMe's system appears to be the best. Their matching procedure isn't as rigid as the others, which may result in false matches, but I believe they have a good confidence rating system which should provide enough guidance when it comes to establishing the likelihood that you are actually related.
- Family Tree DNA uses IBS small segments to determine matches. This sort of rating system can cause good matches to be lost.
- I rate AncestryDNA well below the others when it comes to matching. They phase results and now use a Timber filter to determine IBS segments. AncestryDNA processes as many as 30,000 kits a month. I believe the extra processing they do with the kits affects the accuracy of their match results. They claim their processes have a low error rate. I personally think the error rate is higher than they claim. Their computer system is full of glitches which may also affect the match results? Both my Mom and I lost 3 previously 95% confidence matches ( one was a 3rd cousin 1x removed). A third cousin of mine lost 8 matches in the previously 95% confidence level. After phasing these matches looked strong, the Timber filter eliminated them completely. Timber also pushed a few 95% confidence matches into the Extremely High confidence level. A couple of these matches have extensive trees going back 8 generations. I can't find a common ancestor or even common places with them?
I think it would be best if all of the companies would use the same match criteria as 23andMe, which is at least one segment which is 7 cMs and 700 SNPs. 23andMe sets a cap on the number of matches to avoid the problem AncestryDNA had with massive numbers of matches. I think the cap is a better idea than trying to filter out IBS segments and in the process losing good matches.
Ancestry.com is more of an entertainment site rather than a serious genealogy site. A great blog post explaining the pitfalls of this approach was published this week "Ignorance is Bliss at AncestryDNA". I would still test with them; it's just important to realize their match procedure and confidence levels are flawed. I probably lost half a dozen matches I felt were likely true matches at AncestryDNA when the Timber filter was used. That's not a good thing, but I can live with that because the trees are so helpful.