|
Downloading Segment Match Data
DMT uses segment match data. Each company has different methods of providing you with that data.
On the next pages are instructions on how to download segment match data from Family Tree DNA, 23andMe, MyHeritage DNA and GEDmatch.
Important Note: DNA companies change the format of their segment match data and download procedures from time to time. If DMT is not working as prescribed, please contact me and I'll look at the issue.
Whose segment match files should you download? Try to download any people whose direct relationship you know. You will be assigning the Most Recent Common Ancestor (MRCA) to these people and DMT will be able to compute ancestral lines from them. At GEDmatch, you can download anyone's match file if you subscribe to their Tier 1 services. At the other companies, you only have access to the testers you administer, so you would have to contact the people whose tests you don't have access to, and ask them to download the match data and send it to you.
Here's what's good and bad about the segment match data you can get from each company:
Family Tree DNA:
Good:
-
Allows you to download a person's segment matches with a single click.
-
All of the segment matches for all matching people are downloaded.
-
You get all single matches down to 6 cM.
-
The download at FTDNA usually takes at most a couple of minutes.
Bad:
-
The segment match data does not include the tester's name, so you must add the testers name to cell G1 in the match data file.
-
The segment match data does not contain a unique ID number, so if two people have the same name, e.g. both being John Smith, their results will be mixed together. DMT does its best to detect, inform you of this, and eliminate duplicate matches where possible.
-
You can only download segment match data for the kits you administer. To get the segment match data from other DNA relatives, you will have to contact and ask them to download their segment match data and send it to you.
23andMe
Good:
-
Allows you to download a person's segment matches with a single click.
-
You get all single matches down to 5 cM.
Good and Bad:
-
You can only download segment match data for the kits you administer. To get the segment match data from other DNA relatives, you will have to contact them and ask them to download their segment match data and send it to you. But there is an alternative. The program DNAGedcom can download your segment match data of people in your match list without you contacting them. DNAGedcom charges $5 for a month usage of their program.
Bad:
-
You are limited to the segment matches of the 1500 closest people you match with plus any others you've "connected" with. For $39 a year, you can subscribe to 23andMe+ and get 5000 matches.
-
The segment match data does not contain a unique ID number, so if two people have the same name, e.g. both being John Smith, their results will be mixed together. DMT does its best to detect, inform you of this, and eliminate duplicate matches where possible.
MyHeritage DNA
Good:
-
Allows you to request a person's segment matches with a single click which will send the file to you a few minutes later as an attachment to an email.
-
You get all single matches down to 6 cM.
-
Uses a Match ID number, so each kit is identifiable, even if two people's names are the same. DMT appends part of the Match ID number to the name to ensure uniqueness of the name.
-
The file is grouped by person, with a blank line between people so you can see all the matches of each person together. The people are ordered by highest total shared cM down to lowest.
-
The file gets emailed to you when it is ready, so you don't have to wait online for it to complete.
Bad:
-
MyHeritage's segment match data does not include matches on the X chromsome.
-
MyHeritage uses imputation and stitching techniques to derive their segment matches. As a result, they tend to have larger false segments than other companies. You may want to raise DMT's Minimum Single match limit from 15 cm to 20 or 25 cM.
-
The MyHeritage segment file name depends on what your Windows language is.
-
You can only download segment match data for the kits you administer. To get the segment match data from other DNA relatives, you will have to contact them and ask them to download their segment match data and send it to you.
GEDmatch
Good:
-
Allows you to download a person's segment matches with a single click.
-
Uses a GEDmatch ID number, so each kit is identifiable, even if two people's names are the same. DMT appends the kit number to the name to ensure uniqueness of the name.
-
Includes people who have tested at different companies and all their segment data have been converted to GEDmatch's chromosome mappings so the segment data can be compared.
-
You can download any person's segment matches. You need not be an administrator of their data and do not need to contact the other person to download their data.
Bad:
-
The segment match data does not include the tester's name, but it does include the ID number of the tester. The download is always named csvsegmatch_.csv and does not contain the name of the person or ID number. DMT has to retrieve the name of the tester from other match files.
-
Their segment match report excludes matches between people sharing more than 2100 cM. That means that all parents, children and siblings, and some uncles, aunts, nephews and nieces will be excluded from the match data. You definitely do want these people included. To get around this, DMT includes a "Save GEDmatch 1-1" button so that you can retrieve data via the GEDmatch one-to-one report to get parent, children and sibling match data. It's an extra small pain that GEDmatch shouldn't have to make you do.
-
You are limited to the segment matches of the 10,000 closest people you match with. The default supplied is 1,000 and you have to change it every download if you want 10,000.
-
You need Tier 1 services from GEDmatch to download segment match data. Tier 1 services currently cost $15 a month with a minimum one-month signup or $100 a year.
|
|
