Yes, the 10 cM difference (from 8 to 18) in such a small difference of physical length seems implausible. I calculated a 236,091 SNP difference in the physical length of the segments, and according to these results that total length is about 10 cM. I could not easily find anything online which maps different segment locations to length in cM, though I am sure it’s out there somewhere. It is just worrisome that the comparison makes it look like something is amiss. > On Oct 24, 2015, at 1:15 PM, genealogy-dna-request@rootsweb.com wrote: > > Date: Sat, 24 Oct 2015 11:51:26 -0400 > From: jlerch1@lighttube.net > Subject: [DNA] re FTDNA vs Gedmatch > To: genealogy-dna@rootsweb.com > Message-ID: <20151024115126.vush13734g4o08w4@webmail.lighttube.net> > Content-Type: text/plain; charset=UTF-8 > > To be specific, you're saying that there never can be a stretch where 10 cM is compressed into? 330,000 SNPs?? I don't know.? I know there are some pretty fragile spots.? On all my allegedly pileup spots, the middles which everyone shares is some unknown # but the difference between persons at the ends can be quite large, certainly 1 cM in about 100,000 SNPs. > > DHamill wrote > Subject: Re: [DNA] GENEALOGY-DNA Digest, Vol 10, Issue 576 > To: genealogy-dna@rootsweb.com > Message-ID: <14F5C288-84FF-4323-8A1D-93B5440D9B43@aol.com> > Content-Type: text/plain; charset=utf-8 > > I don?t think these results can both be correct. Not just a difference in criteria for a match or strictness of guidelines etc. If they really are reporting these results, I think there is something computationally rotten in Denmark. > > Maybe you could start by just double-checking these numbers.. just to be sure there are no typos etc involved? > > Does anyone else have a segment with about the same start and stop locations? ? if so how many cM? > >> On Oct 23, 2015, at 5:51 PM, genealogy-dna-request@rootsweb.com wrote: >> >>> -----Original Message----- From: Brooks Family via >>> Sent: Friday, October 23, 2015 11:29 AM >> FTDNA >>> 9 131,456,657 137,335,024 8.85 1955 >>> >>> >>> gedmatch near identical boundaries and SNPs, but cMs are much larger: >>> 9 131,390,868 137,505,316 18.8 1,904 >
Dave I believe that you are counting base pairs rather than SNPs. CentiMorgans are not a physical measurement of length, they are the probability of a crossover at various points along the chromosome. RPaine -----Original Message----- From: David Hamill via Sent: Saturday, October 24, 2015 12:43 PM To: genealogy-dna@rootsweb.com Subject: Re: [DNA] GENEALOGY-DNA Digest, Vol 10, Issue 578 Yes, the 10 cM difference (from 8 to 18) in such a small difference of physical length seems implausible. I calculated a 236,091 SNP difference in the physical length of the segments, and according to these results that total length is about 10 cM. I could not easily find anything online which maps different segment locations to length in cM, though I am sure it’s out there somewhere. It is just worrisome that the comparison makes it look like something is amiss. > On Oct 24, 2015, at 1:15 PM, genealogy-dna-request@rootsweb.com wrote: > > Date: Sat, 24 Oct 2015 11:51:26 -0400 > From: jlerch1@lighttube.net > Subject: [DNA] re FTDNA vs Gedmatch > To: genealogy-dna@rootsweb.com > Message-ID: <20151024115126.vush13734g4o08w4@webmail.lighttube.net> > Content-Type: text/plain; charset=UTF-8 > > To be specific, you're saying that there never can be a stretch where 10 > cM is compressed into? 330,000 SNPs?? I don't know.? I know there are some > pretty fragile spots.? On all my allegedly pileup spots, the middles which > everyone shares is some unknown # but the difference between persons at > the ends can be quite large, certainly 1 cM in about 100,000 SNPs. > > DHamill wrote > Subject: Re: [DNA] GENEALOGY-DNA Digest, Vol 10, Issue 576 > To: genealogy-dna@rootsweb.com > Message-ID: <14F5C288-84FF-4323-8A1D-93B5440D9B43@aol.com> > Content-Type: text/plain; charset=utf-8 > > I don?t think these results can both be correct. Not just a difference in > criteria for a match or strictness of guidelines etc. If they really are > reporting these results, I think there is something computationally rotten > in Denmark. > > Maybe you could start by just double-checking these numbers.. just to be > sure there are no typos etc involved? > > Does anyone else have a segment with about the same start and stop > locations? ? if so how many cM? > >> On Oct 23, 2015, at 5:51 PM, genealogy-dna-request@rootsweb.com wrote: >> >>> -----Original Message----- From: Brooks Family via >>> Sent: Friday, October 23, 2015 11:29 AM >> FTDNA >>> 9 131,456,657 137,335,024 8.85 1955 >>> >>> >>> gedmatch near identical boundaries and SNPs, but cMs are much larger: >>> 9 131,390,868 137,505,316 18.8 1,904 > ------------------------------- 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
You can enter base positions in this calculator. It's for Build 36, which is used by FTDNA and GEDmatch. http://compgen4.rutgers.edu/mapinterpolator Ann Turner On Sat, Oct 24, 2015 at 12:43 PM, David Hamill via < genealogy-dna@rootsweb.com> wrote: > Yes, the 10 cM difference (from 8 to 18) in such a small difference of > physical length seems implausible. > > I calculated a 236,091 SNP difference in the physical length of the > segments, and according to these results that total length is about 10 cM. > > I could not easily find anything online which maps different segment > locations to length in cM, though I am sure it’s out there somewhere. > > It is just worrisome that the comparison makes it look like something is > amiss. > > > > On Oct 24, 2015, at 1:15 PM, genealogy-dna-request@rootsweb.com wrote: > > > > Date: Sat, 24 Oct 2015 11:51:26 -0400 > > From: jlerch1@lighttube.net > > Subject: [DNA] re FTDNA vs Gedmatch > > To: genealogy-dna@rootsweb.com > > Message-ID: <20151024115126.vush13734g4o08w4@webmail.lighttube.net> > > Content-Type: text/plain; charset=UTF-8 > > > > To be specific, you're saying that there never can be a stretch where 10 > cM is compressed into? 330,000 SNPs?? I don't know.? I know there are some > pretty fragile spots.? On all my allegedly pileup spots, the middles which > everyone shares is some unknown # but the difference between persons at the > ends can be quite large, certainly 1 cM in about 100,000 SNPs. > > > > DHamill wrote > > Subject: Re: [DNA] GENEALOGY-DNA Digest, Vol 10, Issue 576 > > To: genealogy-dna@rootsweb.com > > Message-ID: <14F5C288-84FF-4323-8A1D-93B5440D9B43@aol.com> > > Content-Type: text/plain; charset=utf-8 > > > > I don?t think these results can both be correct. Not just a difference > in criteria for a match or strictness of guidelines etc. If they really are > reporting these results, I think there is something computationally rotten > in Denmark. > > > > Maybe you could start by just double-checking these numbers.. just to be > sure there are no typos etc involved? > > > > Does anyone else have a segment with about the same start and stop > locations? ? if so how many cM? > > > >> On Oct 23, 2015, at 5:51 PM, genealogy-dna-request@rootsweb.com wrote: > >> > >>> -----Original Message----- From: Brooks Family via > >>> Sent: Friday, October 23, 2015 11:29 AM > >> FTDNA > >>> 9 131,456,657 137,335,024 8.85 1955 > >>> > >>> > >>> gedmatch near identical boundaries and SNPs, but cMs are much larger: > >>> 9 131,390,868 137,505,316 18.8 1,904 > > > > > > ------------------------------- > 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