How Can Geneologists Caregorically Say For Sure.[last names were not changed at Ellis Island]..?

To put some scale on the amount of data here.

Given a fairly typical assumption of an average from Yaleof 20 hours per linear foot this one regional collection would take 17,000-34,000 person hours or about 16.5 (2080 hour) person years to run through.

Obviously it has an index, and if your search uses that index it will be more efficient and other tools could reduce this time even more.

While this is probably the largest regional collection this is not all of the data that would have to be run through if you are looking for terms that aren’t the index. The time complexity would not be linear to correlate these either. Nor would it “prove” outside of official requests where this happened.

Sure targeted studies can show that it was uncommon or even rare, but I have already acknowledged that. And no, changes weren’t made out of spite etc…

But yes, if you can’t point to a study that did more than look at the manifests we will be an an impasse. Simply no careful research has been done to prove an absolute claim that it NEVER happened even through clerical error.

Feel free to provide a cite that documents even a claimed detection power of the applied methods or heck even offers a confidence metric and I can consider the null result as evidence of absence.

I have tried to find any such study myself but have failed, but confirmation bias will do that to you and I would appreciate it if I someone can share a link.

It was a school master instead of a marm, but this is how my maternal great-grandfather’s last name changed. He and his younger sister, the two youngest by far of several children, were taught by the teacher in a one room school house the French spelling of their last name, not the Portuguese spelling, when they were learning to write. So Great-Grampy and great-aunt Amy used one spelling which they passed down to their children and grandchildren, and all of their older brothers and their progeny use the original spelling.