A link from genealogyblog.com:

An Open Letter to Leaders in the Online Family Tree Business:

This letter makes interesting reading. I think the proposal of a single, shared resource for family history is a great idea. Finding information for our trees can be a time-consuming and expensive task, and an especially difficult for those of us working 9-5, or otherwise unable to get to the Record Offices.

While great in principle, there is a fundamental weakness in the approach: variable data quality.

“History Is Written By The Victors” as the often mis-quoted saying goes. In history, even relatively recent history, there is no such thing as truth. All we can ever have is a block of evidence. Even first-hand reporting can’t be completely relied upon. Eye witnesses subconsciously re-mould their experiences to fit in with their personal beliefs (ref: Eye Witness Testimony – Simply Psychology blog)

In family history we have a similar problem: we often subconsciously re-mould the data we find to fit it into our trees. The excitement of finding a good potential match is sometimes hard to resist. We’ve all done it. We’ve all had a link where enough (or any!) evidence can’t be found, but we just know that it’s the ancestor we’ve been hunting.

That’s not the same as evidence though, and that’s the problem.

When I first started out in genealogy I got some great advice from a very experienced genealogist  called Jean Cole. Jean told me that data doesn’t have value unless it has “two supporting pieces of evidence”. (book link – Tracing Your Family Tree)

So, that means for example that a birth certificate alone is not enough to identify an ancestor, you also need some corroborating information. That could be, for example, a census, or a marriage certificate, or even personal testimony in some cases. The point is that none of the data or items of proof stand on their own.

I’ve been researching my own family history for over 20 years, on and off. My data has the same quality problems as everyone else’s. Not all of the links I made in those early days have stood the test of further investigation. When I started researching I was a total beginner, I had no skills, but I collected a lot of data. The thing is though, that data stayed on my computer. There simply weren’t any tree sharing sites like Family Search and Ancestry, so those early mistakes were not published.

Nowadays someone can start their research online, collate a lot of data very quickly, and publish it to the world equally quickly. Other people then take that published tree as “evidence” for their own research.

If we are going to have a Single Public Family Tree we need to significantly raise the general level of quality in family history research, both in terms of what data is available on-line, and in our assessment and handling of that data.