Author Topic: Ancestry removing matches less than 8cM  (Read 6801 times)

Offline Gadget

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Re: Ancestry removing matches less than 8cM
« Reply #45 on: Sunday 19 July 20 13:28 BST (UK) »
It's not measured in integers but fractions but they display them as integers - thus 7.5-7.9999999999999 will be rounded to 8 and 7.4 is likely to be rounded down to 7.

I've come across it in the 20cM matches.

PS - it's quite common

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Online LizzieL

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Re: Ancestry removing matches less than 8cM
« Reply #46 on: Sunday 19 July 20 15:22 BST (UK) »
Which of course means half the matches recorded as 8 will go as they are actually 7.5 to 7.99999.
Berks / Oxon: Eltham, Annetts, Wiltshire (surname not county), Hawkins, Pembroke, Partridge
Dorset / Hants: Derham, Stride, Purkiss, Scott, Sibley
Yorkshire: Pottage, Carr, Blackburn, Depledge
Sussex: Goodyer, Christopher, Trevatt
Jersey: Fowler, Huelin, Scott
Essex/Herts: Livermore, Holgate, Law, Day, Myson, Boyton
Norfolk/Suffolk: Stone, Alexander, Tipple, Ingate

Offline Gadget

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Re: Ancestry removing matches less than 8cM
« Reply #47 on: Sunday 19 July 20 15:35 BST (UK) »
Yep and there must be a few 5.5 to 5.99999999 (recurring) that have been hiding too  ;D
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Offline Janethepain

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Re: Ancestry removing matches less than 8cM
« Reply #48 on: Sunday 19 July 20 15:36 BST (UK) »
I know it is quite common, but that does not make it right.

If a given match is classified as having 8cM of DNA matching, under normal understanding, you would read 8 to represent anything from 8 exactly to 8.9999 etc., but not to be under 8, that should be 'lumped in the 7cM slot!

Unless they expain it somewhere obvious, that customers can see, then you don't expect that Cm's will be rounded up or down to the nearest whole number, as in 7 actually representing 6.501 to 7.500 etc..

Well at least I would not expect that!

However, you cant argue the point with Ancestry ( well, not expectiong to win the argument anyway), so better get back to the day job!

That is tagging my vulnerable matches!
Allison - Rumford Stirlingshire & Ireland
Quinn - Rumford, Glasgow, Monklands & Tyrone
Convoy - Rumford, Monklands & Tyrone
Burke - Glasgow, Clifden Galway
Duffy - Cleland Lanarkshire, Monklands, Falkirk, Ireland
Curran - Cleland, Ireland
Reynolds - Cleland, Shettleston, Tollcross, Antrim
McDermott - Cleland, Shotts, (London)Derry

Offline GailB

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Re: Ancestry removing matches less than 8cM
« Reply #49 on: Monday 20 July 20 12:16 BST (UK) »
On facebook maths problems - posters always moan about 'old' maths and 'new' maths, and the rules involved (Podemas - the rules of operations etc), and those who know maths of course say maths is maths ( or math, if you are american), and there only ever is one right answer, which ever way, and whenever,  you learned maths!  However, Ancestry seems to have its own wee version here!

Honestly, I remember back a few itterations ago of the DNA screens ,when on a screen that told you about a matches DNA in more detail, it told you more exactly  the match figure (eg 19.5). and the dependability of the match (eg high/low/medium), and what that meant (eg nearly 100% likely to be a true match).  Not all changes have been for the better!  Especially when at one time it is under a border line (eg 20), but sometimes over it. Crazy.

How can a value measured to be under 8.0* be classed at other times as 8 or over 8!

* indcating 'recurring', that is as many 0's as you like!!

Ah well back to checking my 8's now.  I an happy (relatively) with 7's, but decided to deal with 8's before tackling 6's, as there will be even more 6's..... Ahh

Jane

I keep a record of my matches on a spreadsheet when I know how they are related from back when Ancestry included decimal places.

I have a 4C1R (PV) who matches me at 20.1cM and is included in my 4th-6th cousins but now shows just as 20cM, whereas another 4C1R, MS matches me at exactly 20cM and is included in my distant cousins.

Therefore, the when Ancestry delete those who match 6-7cM any at 8cM should remain as they would actually match 8.1cM or more, whereas those who are 6-7cM would only match up to 7cM exactly.
Armitage, Atherton, Barton, Beck, Bradshaw, Brumfitt, Chetwin, Conalty, Connolly, Connor(s), Davidson, Hilton, Hoey, Johnson, Jones, Knight, Lester, McDonald, Molyneux, Morris, Pownall, Rushton, Spark, Stanley, Tunstall, Welsby, West, Wharton, Williams, Wilson, Windridge, Windstandley

Offline Janethepain

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Re: Ancestry removing matches less than 8cM
« Reply #50 on: Monday 20 July 20 12:34 BST (UK) »
Hope that's how it goes!!

On a related issue,matches in the 3 lowest cM levels (6-8), are not necessarily very distant ancestors. I have a 3rd cousin 1x removed with just 6 cM matching. Also a second cousin 2x removed.  They are my lowest  two common ancestor matches! I have 4th Cousins and 3rd Cousins 2x removed in this band too!  Quite easy to trace through the mainly Scottish records that are involved in tracing the connections! Once you find a surname to look for!
Allison - Rumford Stirlingshire & Ireland
Quinn - Rumford, Glasgow, Monklands & Tyrone
Convoy - Rumford, Monklands & Tyrone
Burke - Glasgow, Clifden Galway
Duffy - Cleland Lanarkshire, Monklands, Falkirk, Ireland
Curran - Cleland, Ireland
Reynolds - Cleland, Shettleston, Tollcross, Antrim
McDermott - Cleland, Shotts, (London)Derry

Online LizzieL

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Re: Ancestry removing matches less than 8cM
« Reply #51 on: Monday 20 July 20 13:06 BST (UK) »

I keep a record of my matches on a spreadsheet when I know how they are related from back when Ancestry included decimal places.

I have a 4C1R (PV) who matches me at 20.1cM and is included in my 4th-6th cousins but now shows just as 20cM, whereas another 4C1R, MS matches me at exactly 20cM and is included in my distant cousins.

Therefore, the when Ancestry delete those who match 6-7cM any at 8cM should remain as they would actually match 8.1cM or more, whereas those who are 6-7cM would only match up to 7cM exactly.

Did you have you any just below an integer. e.g 19.9 ? If so, were they rounded up to 20 or just dec places just chopped so they would become 19?
Berks / Oxon: Eltham, Annetts, Wiltshire (surname not county), Hawkins, Pembroke, Partridge
Dorset / Hants: Derham, Stride, Purkiss, Scott, Sibley
Yorkshire: Pottage, Carr, Blackburn, Depledge
Sussex: Goodyer, Christopher, Trevatt
Jersey: Fowler, Huelin, Scott
Essex/Herts: Livermore, Holgate, Law, Day, Myson, Boyton
Norfolk/Suffolk: Stone, Alexander, Tipple, Ingate

Offline GailB

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Re: Ancestry removing matches less than 8cM
« Reply #52 on: Monday 20 July 20 13:09 BST (UK) »

Did you have you any just below an integer. e.g 19.9 ? If so, were they rounded up to 20 or just dec places just chopped so they would become 19?

Actually, I've just done some further checking and it is a worry, I do have a 19.7cM which is rounded up to 20cM so we may lose some of the 8cMs.

ADDED: a 19.4cM has been rounded down to 19cM
Armitage, Atherton, Barton, Beck, Bradshaw, Brumfitt, Chetwin, Conalty, Connolly, Connor(s), Davidson, Hilton, Hoey, Johnson, Jones, Knight, Lester, McDonald, Molyneux, Morris, Pownall, Rushton, Spark, Stanley, Tunstall, Welsby, West, Wharton, Williams, Wilson, Windridge, Windstandley

Offline Gadget

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Re: Ancestry removing matches less than 8cM
« Reply #53 on: Monday 20 July 20 13:36 BST (UK) »
The commonest method of rounding is
 .5 - .9 = round up
 .4 and below= round down

(including the .999999  and .000000001 recurring)
Census &  BMD information Crown Copyright www.nationalarchives.gov.uk and GROS - www.scotlandspeople.gov.uk