# Thread: The YFull TMRCA vs. Iain McDonald methods

1. ## The YFull TMRCA vs. Iain McDonald methods

YFull uses a term called the "formed" date. I have read their definition and the formed date of a subclade is just date of the TMRCA of the parent clade. However, although the labeling does include "formed", in the detailed tables they show their calculations and have ages that some call "formed".

Below is a explanation. I understand how the tables/calculations work, I think, but I don't see these dates as particularly unique versus other SNP age estimates and their calculations. I've been told these are exclusives from YFull.

Please convince me of their value, but do so relative to the method that Iain McDonald uses. Is there really any added value in the term "formed" date? and are sub-table calculations showing the relative age between brother subclades any more useful than using Iain McDonald's TMRCA age estimates for subclades?

I do understand relative aging by SNP counting, either bottoms-up or tops-down but I do not think we have enough accuracy (because of variability in mutation rates) that getting into some of this precision is valuable anyway.

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https://www.dropbox.com/s/9k5g3mhhkk...4mike.jpg?dl=0

YFull provides two estimates each for “formed” and “TMRCA”.

The estimate provided in the info tables (“Formed 2” on dropbox .jpg above) is not labeled as such by YFull and is not readily available from any source other than YFull, to the best of my knowledge. If nothing else, it does provide a relative estimate of the order of formation of the children of an SNP. For example:

4814 YBP R-L21

4968 YBP ….. R-DF63
5096 YBP ….. ….. R-CTS6919
4529 YBP ….. ….. R-Y10997

4669 YBP ….. R-DF13
5527 YBP ….. ….. R-DF49
5476 YBP ….. ….. R-FGC19914
5280 YBP ….. ….. R-L679
5160 YBP ….. ….. R-CTS3386
5026 YBP ….. ….. R-Y14049
4855 YBP ….. ….. R-FGC5496
4601 YBP ….. ….. R-Y5717
4576 YBP ….. ….. R-CTS2501
4564 YBP ….. ….. R-CTS1751
4526 YBP ….. ….. R-Y16233
4483 YBP ….. ….. R-Z253
4454 YBP ….. ….. R-Z16503
4420 YBP ….. ….. R-Y9097
4396 YBP ….. ….. R-DF1
4289 YBP ….. ….. R-S1026
4285 YBP ….. ….. R-DF21
4275 YBP ….. ….. R-BY4048
4218 YBP ….. ….. R-Y5305
4210 YBP ….. ….. R-L1335
4133 YBP ….. ….. R-Z251
3923 YBP ….. ….. R-Y9090
3832 YBP ….. ….. R-FGC11134
3716 YBP ….. ….. R-S1051
3567 YBP ….. ….. R-Y30336
3294 YBP ….. ….. R-Z14303
3097 YBP ….. ….. R-Z255
2774 YBP ….. ….. R-L371

4236 YBP ….. R-A5846
4050 YBP ….. ….. R-Y16251

2949 YBP ….. R-A7906
2260 YBP ….. ….. R-FGC52350
1835 YBP ….. ….. R-A7908

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Regardless, is the fact that YFull provides "formed" dates a major exclusive value-add for their method?

2. Originally Posted by Mikewww
YFull uses a term called the "formed" date. I have read their definition and the formed date of a subclade is just date of the TMRCA of the parent clade. ...

Regardless, is the fact that YFull provides "formed" dates a major exclusive value-add for their method?
Here are two explanatory web pages from YFull:

https://www.yfull.com/faq/what-yfull...n-methodology/

https://www.yfull.com/faq/how-does-y...-tmrca-and-ci/

Originally Posted by YFull
Subclade "formed" age: The TMRCA (time to most recent common ancestor) of a subclade is used as the "formed" age of each branch of the subclade. Stated otherwise, the formed age of a branch is the same as the TMRCA of the "parent" subclade of that branch.

3. Iain has published a technical explanation of the process he utilizes to arrive at his dates at: http://www.jb.man.ac.uk/~mcdonald/ge...ne-summary.pdf

Please note it is very heavy in the statistical analysis and thus way over my pay grade.

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5. I'm no expert. I like YFull. I paid for their services. But I tend to think Iain MacDonald is probably closer to right. Don't expect me to argue either way. I'm too damned tired.

6. I would like to provide a case study of yfull's, and Alex Williamson's SNP dating methods (based on McDonald's method) vs STR dating methods, using a relatively recent branch I'm quite familiar with (in the last 1000 years). As such it's in that area where both methods are useful (IMO once your get beyond 1000-1500 years the STR method tends to underestimate ages)

The branch is called FGC47884 on yfull and ytree.

https://www.yfull.com/tree/R-FGC47884/
http://ytree.net/BlockInfo.php?blockID=2638

Background: One man on this branch has done FGC Y Elite 2.1 and the other has done BigY and both have done FTDNA's 111 marker test. What is known from genealogical records is their MRCA had to have lived prior to 1720 AD.

1. Their Genetic Distance = 4 at 111 markers. According to FTDNA
A 107/111 match indicates a genealogical relationship. Most matches at this level are related as 10th or more recent cousins, and over half will be 6th or more recent cousins. This is well within the range of traditional genealogy.
From genealogical records the closest these two men could possibly be is 8th cousins...more likely it further back...10th cousins or earlier.

2. Using the mymcgee tool with the FTDNA 111 markers at http://www.mymcgee.com/tools/yutility111.html set at 95% probability provides a TMRCA of 480 years (1470 AD).

3. Both men have submitted their data to yfull. Using Yfull's STR matching tool they had have 19 out of 255 SNPs that are different for a distance of .075.

4. I combined the 111 marker and Yfull STR data to come up with 319 STRs to compare of which 24 had different values. Using the default settings at http://dna.cfsna.net/HAP/MLE.htm website and the 319 STRs provided TMRCA of 470 years (280 - 660 years ago). 1480 AD (1290 to 1670 AD)

5. One man took the FGC Y Elite 2.1 test and has 7 private SNPs in McDonald's BED region and 5 in the combBed region (used by Yfull for dating). The other took BigY and has 2 private SNPs in both McDonald's BED and the combBed region.

-On Yfull: TMRCA for this branch is 517 ybp or 1433 AD; with 95% CI of 900 AD to 1725 AD rounded to 500 ybp

-Alex Williamson's site
Using the aging method developed by Iain McDonald, the median age of this block is 738.557 YBP (1212 AD). The 95% confidence interval is 740 AD to 1564 AD.
So compared to the 319 STR dating method (470 ybp):
- YFull's best guess date is ~49 years older
- Alex Williamson best guess date is 269 years older

In prior discussions with Iain McDonald, he stressed the 95% CI date range is more important than the best guess date. As such, YFull's and Alex Williamson's date ranges overlap the STR date (1480 AD for 319 STR method vs upper limit of 1725 AD for yfull and 1564 AD for Ytree.net).

This is not to imply that the STR dating method is more accurate than the SNP methods above. In this study of 111 markers, the STR method has proven to be quite variable. http://linealarboretum.blogspot.com/...er-at.html?m=1
While 111 markers aided in fine tuning our connectivity to those sharing our genetic and genealogical roots, genetic distance was not an accurate predictor of most relationships. Outliers can and do happen, as experienced with a GD=0; however, 78% of the participants at a GD=0 fell within the predicted level of six generations or less with a p ≤ .01, Two did not, and as explained earlier, this was due to convergence. We have seen close relatives (5th cousins and closer) having genetic distances up to 5, while 13th cousins, once removed have a GD=0.
But as I've been able to compare 319 STRs between these two men, I have to say I tend to place more confidence in this method's date.

If the MRCA for these two men is ever discovered (hundreds of man hours on my part have so far been to no avail), it will be interesting to revisit this branch.

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8. Originally Posted by MitchellSince1893
I would like to provide a case study of yfull's, Iain McDonald's, and Alex Williamson's SNP dating methods vs STR dating methods, using a relatively recent branch I'm quite familiar with (in the last 1000 years). As such it's in that area where both methods are useful (IMO once your get beyond 1000-1500 years the STR method tends to underestimate ages)

The branch is called FGC47884 on yfull and ytree and R-BY12085 by Iain McDonald and FTDNA.

https://www.yfull.com/tree/R-FGC47884/
http://ytree.net/BlockInfo.php?blockID=2638

Background: One man on this branch has done FGC Y Elite 2.1 and the other has done BigY and both have done FTDNA's 111 marker test. What is known from genealogical records is their MRCA had to have lived prior to 1720 AD.

1. Their Genetic Distance = 4 at 111 markers. According to FTDNA
From genealogical records the closest these two men could possibly be is 8th cousins...more likely it further back...10th cousins or earlier.

2. Using the mymcgee tool with the FTDNA 111 markers at http://www.mymcgee.com/tools/yutility111.html set at 95% probability provides a TMRCA of 480 years (1470 AD).

3. Both men have submitted their data to yfull. Using Yfull's STR matching tool they had have 19 out of 255 SNPs that are different for a distance of .075.

4. I combined the 111 marker and Yfull STR data to come up with 319 STRs to compare of which 24 had different values. Using the default settings at http://dna.cfsna.net/HAP/MLE.htm website and the 319 STRs provided TMRCA of 470 years (280 - 660 years ago). 1480 AD (1290 to 1670 AD)

5. One man took the FGC Y Elite 2.1 test and has 7 private SNPs in McDonald's BED region and 5 in the combBed region (used by Yfull for dating). The other took BigY and has 2 private SNPs in both McDonald's BED and the combBed region.

-On Yfull: TMRCA for this branch is 517 ybp or 1433 AD; with 95% CI of 900 AD to 1725 AD rounded to 500 ybp

-Alex Williamson's site

So compared to the 319 STR dating method (470 ybp):
- YFull's best guess date is ~49 years older
- Alex Williamson best guess date is 269 years older
- Iain McDonald's best guess date is 492 years older

In prior discussions with Iain, he stressed the 95% CI date range is more important than the best guess date. As such, YFull's and Alex Williamson's date ranges overlap the STR dates, and McDonald's is just outside of it (1480 AD for 319 STR method vs Iain's upper range of 1455 AD).

This is not to imply that the STR dating method is more accurate than the SNP methods above. In this study of 111 markers, the STR method has proven to be quite variable. http://linealarboretum.blogspot.com/...er-at.html?m=1

But as I've been able to compare 319 STRs between these two men, I have to say I tend to place more confidence in this method's date.

If the MRCA for these two men is ever discovered (hundreds of man hours on my part have so far been to no avail), it will be interesting to revisit this branch.
I tried copy and pasting my str data. I just get a bunch of html text. Even when I paste it here, it still doesn;t paste as a chart or anything. What am I missing?

9. Originally Posted by MitchellSince1893
I would like to provide a case study of yfull's, Iain McDonald's, and Alex Williamson's SNP dating methods vs STR dating methods, using a relatively recent branch I'm quite familiar with (in the last 1000 years). As such it's in that area where both methods are useful (IMO once your get beyond 1000-1500 years the STR method tends to underestimate ages)

The branch is called FGC47884 on yfull and ytree and R-BY12085 by Iain McDonald and FTDNA.

https://www.yfull.com/tree/R-FGC47884/
http://ytree.net/BlockInfo.php?blockID=2638

Background: One man on this branch has done FGC Y Elite 2.1 and the other has done BigY and both have done FTDNA's 111 marker test. What is known from genealogical records is their MRCA had to have lived prior to 1720 AD.

1. Their Genetic Distance = 4 at 111 markers. According to FTDNA
From genealogical records the closest these two men could possibly be is 8th cousins...more likely it further back...10th cousins or earlier.

2. Using the mymcgee tool with the FTDNA 111 markers at http://www.mymcgee.com/tools/yutility111.html set at 95% probability provides a TMRCA of 480 years (1470 AD).

3. Both men have submitted their data to yfull. Using Yfull's STR matching tool they had have 19 out of 255 SNPs that are different for a distance of .075.

4. I combined the 111 marker and Yfull STR data to come up with 319 STRs to compare of which 24 had different values. Using the default settings at http://dna.cfsna.net/HAP/MLE.htm website and the 319 STRs provided TMRCA of 470 years (280 - 660 years ago). 1480 AD (1290 to 1670 AD)

5. One man took the FGC Y Elite 2.1 test and has 7 private SNPs in McDonald's BED region and 5 in the combBed region (used by Yfull for dating). The other took BigY and has 2 private SNPs in both McDonald's BED and the combBed region.

-On Yfull: TMRCA for this branch is 517 ybp or 1433 AD; with 95% CI of 900 AD to 1725 AD rounded to 500 ybp

-Alex Williamson's site

So compared to the 319 STR dating method (470 ybp):
- YFull's best guess date is ~49 years older
- Alex Williamson best guess date is 269 years older
- Iain McDonald's best guess date is 492 years older

In prior discussions with Iain, he stressed the 95% CI date range is more important than the best guess date. As such, YFull's and Alex Williamson's date ranges overlap the STR dates, and McDonald's is just outside of it (1480 AD for 319 STR method vs Iain's upper range of 1455 AD).

This is not to imply that the STR dating method is more accurate than the SNP methods above. In this study of 111 markers, the STR method has proven to be quite variable. http://linealarboretum.blogspot.com/...er-at.html?m=1

But as I've been able to compare 319 STRs between these two men, I have to say I tend to place more confidence in this method's date.

If the MRCA for these two men is ever discovered (hundreds of man hours on my part have so far been to no avail), it will be interesting to revisit this branch.
I don't understand the technicalities very well but some of the estimated TMRC ancestor dates on my paternal line of descent I'm sceptical about, particularly numerous surnames of apparently both Welsh and Anglo Saxon (or old English) origin which suggests to me that the dates or some may be much earlier than is currently indicated or at least at the earlier end of the range.
Of course I may be wrong (probably am) and pending results may reveal more.

10. Please Note: Iain McDonald and YFull both create the age estimates from the Big Y (and in the case of YFull, the FGC) data submitted to them. If they don't have a good representation of the whole clade, then their analysis would be inaccurate.

This affects the youngest clades much more so than the ages of clades such as P312 or U106.

As I reported elsewhere, Iain and Greg Magoon have had some discussions regarding incorporating FGC results into his age analysis. The recent Build38 conversion may well delay this effort (as time spent dealing with the conversion is time which is not available to work on incorporating FGC results).

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12. Originally Posted by Dibran
I tried copy and pasting my str data. I just get a bunch of html text. Even when I paste it here, it still doesn;t paste as a chart or anything. What am I missing?
If you are referring to the my mcgee tool, go to the ftdna str project page you are member of and copy your row and at least two other sample'ss rows and paste it in the mymcgee tool

13. Originally Posted by MitchellSince1893
I would like to provide a case study of yfull's, Iain McDonald's, and Alex Williamson's SNP dating methods vs STR dating methods, using a relatively recent branch I'm quite familiar with (in the last 1000 years). As such it's in that area where both methods are useful (IMO once your get beyond 1000-1500 years the STR method tends to underestimate ages)

The branch is called FGC47884 on yfull and ytree and R-BY12085 by Iain McDonald and FTDNA.

https://www.yfull.com/tree/R-FGC47884/
http://ytree.net/BlockInfo.php?blockID=2638

.
My apologies. I've made a mistake above....confusing FGC47884 as being the same branch.as BY12085...They are in fact parallel branches of FGC12401....shouldn't post when not feeling well.

I have edited my post above to remove the BY12085 data and associated McDonald dating method

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