Generally Ancestry is around 10% lower in total cM count on average than you would see on GEDMatch - but this will depend on your GEDMatch settings of course and will probably change depending on the individual kit. The reason is the algorithm which Ancestry uses. It tries to take account of pile up regions and does some sort of statistical phasing. I am not sure anyone knows exactly how it works. Often they will show more segments than say GEDMatch because they remove pileup regions and this causes longer match segments to be broken in some cases. The worst example of this is for parent/child where there should really only be 22 shared segments (or perhaps a few more) but ancestry can show much higher numbers. If you run exactly the same raw DNA through 23andMe and FTDNA then you are also likely to see a different result because of the algorithms they use. Jon Masterson Wales UK, Florida US jon@scruffyduck.co.uk Gedmatch: A488362, M938817 Surnames: Cannon, Coulter, Clinton, Dryman, Lance, Mabey, Pryor, Wrixon Locations: England, Illinois, Kentucky, Texas, Utah, Virginia On 28/12/2015 14:58, Patti Easton via wrote: > Good Day- > > > > Can someone explain to me why there is a significant variation in cM match > amounts from Ancestry to gedmatch, when it is the same Ancestry kit that was > uploaded to gedmatch? For instance, I have a match that shows 34cM and 3 > segments on Ancestry, but records as 46.3 cM on 3 segments on gedmatch. > Granted it is a small match, but that is a variance of 12 cM, more than 25%. > If this is how it reports, does the variance % decrease for larger matches? > > > > Thank you! > > Regards, > > Patti Easton > > > > > ------------------------------- > To unsubscribe from the list, please send an email to GENEALOGY-DNA-request@rootsweb.com with the word 'unsubscribe' without the quotes in the subject and the body of the message

Thank you so much! I knew someone here would have an answer. I appreciate the help. Regards, Patti -----Original Message----- From: genealogy-dna-bounces@rootsweb.com [mailto:genealogy-dna-bounces@rootsweb.com] On Behalf Of Jon Masterson via Sent: Monday, December 28, 2015 8:47 AM To: genealogy-dna@rootsweb.com Subject: Re: [DNA] Variation in cM match amounts Generally Ancestry is around 10% lower in total cM count on average than you would see on GEDMatch - but this will depend on your GEDMatch settings of course and will probably change depending on the individual kit. The reason is the algorithm which Ancestry uses. It tries to take account of pile up regions and does some sort of statistical phasing. I am not sure anyone knows exactly how it works. Often they will show more segments than say GEDMatch because they remove pileup regions and this causes longer match segments to be broken in some cases. The worst example of this is for parent/child where there should really only be 22 shared segments (or perhaps a few more) but ancestry can show much higher numbers. If you run exactly the same raw DNA through 23andMe and FTDNA then you are also likely to see a different result because of the algorithms they use. Jon Masterson Wales UK, Florida US jon@scruffyduck.co.uk Gedmatch: A488362, M938817 Surnames: Cannon, Coulter, Clinton, Dryman, Lance, Mabey, Pryor, Wrixon Locations: England, Illinois, Kentucky, Texas, Utah, Virginia On 28/12/2015 14:58, Patti Easton via wrote: > Good Day- > > > > Can someone explain to me why there is a significant variation in cM > match amounts from Ancestry to gedmatch, when it is the same Ancestry > kit that was uploaded to gedmatch? For instance, I have a match that > shows 34cM and 3 segments on Ancestry, but records as 46.3 cM on 3 segments on gedmatch. > Granted it is a small match, but that is a variance of 12 cM, more than 25%. > If this is how it reports, does the variance % decrease for larger matches? > > > > Thank you! > > Regards, > > Patti Easton > > > > > ------------------------------- > To unsubscribe from the list, please send an email to > GENEALOGY-DNA-request@rootsweb.com with the word 'unsubscribe' without > the quotes in the subject and the body of the message ------------------------------- To unsubscribe from the list, please send an email to GENEALOGY-DNA-request@rootsweb.com with the word 'unsubscribe' without the quotes in the subject and the body of the message