Patti The best way to think of it is that there is less chance of error when you work with longer matching segments. The more SNPs and cM the better. This is a rough estimate of how the error rate changes for smaller segment sizes. 11 cM or greater matching segment: >99% IBD, <1% IBS 10 cM matching segment: 99% IBD, 1% IBS 9 cM matching segment: 80% IBD, 20% IBS 8 cM matching segment: 50% IBD, 50% IBS 7 cM matching segment: 30% IBD, 70% IBS 6 cM matching segment: 20% IBD, 80% IBS 5 cM matching segment: 5% IBD, 95% IBS 4 cM matching segment: ca 1% IBD, ca 99% IBS IBS = Identical By State = by chance IBD = Identical By Descent = inherited RPaine -----Original Message----- From: Patti Easton via Sent: Thursday, January 7, 2016 5:33 AM To: 'Ann Turner' ; genealogy-dna@rootsweb.com Subject: Re: [DNA] segments and cM at AncestryDNA Thank you for the reply Ann. So when looking at results from Ancestry uploaded to gedmatch, does that mean that the chromosome browser comparisons would be faulty? How much error should one expect? Is this just minutia, or would it factor into comparisons? Is this why Ancestry has no chromosome browser? Thank you again, Patti -----Original Message----- From: genealogy-dna-bounces@rootsweb.com [mailto:genealogy-dna-bounces@rootsweb.com] On Behalf Of Ann Turner via Sent: Thursday, January 7, 2016 5:51 AM Cc: DNA Genealogy Mailing List <genealogy-dna@rootsweb.com> Subject: Re: [DNA] segments and cM at AncestryDNA You are correct about the biological reality. Segments do not jump back and forth. However, the DNA results (e.g. CT) you receive for a particular SNP are a "genotype." The DNA is chopped into tiny pieces before analysis, which uses probes to detect the presence of a particular allele. The only thing we can tell is that a C is present in some pieces and a T is present in other pieces. Computer algorithms attempt to predict which SNPs are traveling together as a package on a single chromosome (a haplotype) but they don't always get it right. Ann Turner On Thu, Jan 7, 2016 at 7:23 AM, Patti Easton <amharach@msn.com> wrote: > Ann, > > I really appreciated this article. I watch this list as an eager > novice, knowing I have a steep learning curve, and having gained much > knowledge from the talented people who contribute here. Hopefully > this is appropriate to ask here, again given my novice status. > > What I have trouble wrapping my head around in this article, > particularly given the DNA doesn't lie, DNA is a fact and end all, be > all, is how does Germline allow matches to jump back and forth between > segments? Isn't this counter intuitive to something directed at > extracting genetic code? And without asking too much of the scientific end, how is that even possible. > How can DNA move to other sections? > > Perhaps DNA isn't as black and white as I have been led to view it. I > don't see it as fluid. But while coding appears to not fluctuate, I > guess I am seeing that perhaps the testing makes it so. > > Thank you! > Regards, > Patti Easton > > > > > -----Original Message----- > From: genealogy-dna-bounces@rootsweb.com > [mailto:genealogy-dna-bounces@rootsweb.com] On Behalf Of Ann Turner > via > Sent: Wednesday, January 6, 2016 8:05 PM > To: DNA Genealogy Mailing List <GENEALOGY-DNA@rootsweb.com> > Subject: [DNA] segments and cM at AncestryDNA > > This blog post explains some of the questions we've raised about the > number of shared cM and segments at AncestryDNA and how they compare > to numbers seen at GEDmatch, 23andMe, and FTDNA. > > > http://blogs.ancestry.com/techroots/behind-the-new-ancestrydna-feature > -amoun > t-of-shared-dna/ > > Ann Turner > > ------------------------------- > 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 ------------------------------- 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