Colin You should get in touch with Ron Ferguson who has recently registered the surname FERGUSON with the Guild of One-Name Studies. He might be able to give you a better idea of the distribution of the surname in the UK. You can see his profile page here: http://www.one-name.org/profiles/ferguson.html If all your project members are in the US then you will not have a representative sample of Fergusons in your project. Only a small subset of the population of any given surname emigrated to America. The ones who did go to America were often very successful with very large families and literally thousands of descendants. Your American project members will therefore greatly distort the picture for your surname, and you will only be capturing a small snapshot of the true genetic diversity of the surname. You will need to focus your recruiting efforts on the UK, Australia and New Zealand. If you've got 20 main genetic groups in the US you might well find that you will have 200 or more groups if you were to test large numbers of non-US Fergusons. You might also find the article by Chris Pomery in the autumn/fall 2009 issue of the Journal of Genetic Genealogy of interest: http://www.jogg.info/52/index.html The techniques he describe will not be applicable to a surname of your size, but you might be able to extrapolate from his figures. Debbie Kennett http://www.familytreedna.com/public/CruwysDNA In a message dated 10/09/2010 16:50:20 GMT Daylight Time, colin.fergie@gmail.com writes: I estimate that there are 300,000 Ferguson and variants worldwide with slightly more than half of these resident in the US. We only have 250 participants in project which with 150,000 men to sample seems ridiculously small. However, I estimate further that back about 1600 there were only 5,000 Ferguson and 80% of these were in Scotland. If you assume that an average household of 5 then that equates to 1,000 heads of household as progenitors of all 300,000 Ferguson alive today. See http://dna.cfsna.net/Demographics.htm One number in particular that I struggle to estimate is how many of those 1,000 heads of household would we call related to one another. If that number is one in five then then I am down to only 200 earliest known ancestors that need be tested to characterize today's population of Ferguson. A reasonable sample size at least seems attainable. In our project we have about 20 different groupings of Ferguson each sharing their own ancestor about 800 years ago; 400 years the time back from present to our 1600s progenitors and another 400 years as a TMRCA for the 1600s progenitors accounting for the one in five as above. The 20 different groups referred to account for about half our participants, the remainder fall in small groups or don't match other participants. Relative to 200 earliest known ancestors our sample size is still small but at least not ridiculously so. Am I on track?