Sometimes when researching, you have to punt.
I am very appreciative of the flexibility of Ancestry's search engine. On many databases, the surname field is required, but not at Ancestry. You can search for everyone named "John" across all their databases. The over 45 million results in their census databases alone probably isn't very useful, unless you were curious about the popularity of the name.
I remember last year I was searching for descendants of my great great grandfather, Selig Dudelsack's brother, Julius. I found Julius (who had changed his surname to Odelsohn) in the 1900 St. Louis census, and his oldest daughter was named Pearl. Pearl wasn't in the Odelsohn household in 1910. From her age in 1900 I knew the odds were that she had gotten married - but I had no clue who to.
So I punted with the information I did have
First name: Pearl
Place of Birth: Russia
Year of Birth: 1884 +- 1
There was 1 result, and it was in St. Louis: Pearl Feldman. I went to the Missouri Death Certificates online, and found hers. Her father was Julius Odelsohn. The punt worked. (And a few months later when I looked up her obituary in the St. Louis Post Dispatch, I found about 100 living cousins.)
So today my mother gave me an assignment. She wanted to know where the two children of one of her cousins were. I had their full names from the Texas Birth Index. The son was easy to find - alas, in the Social Security Death Index. The daughter was more difficult, as daughters often are. And since she was born in 1940, there were no censuses to search. But Ancestry does have a Public Records Index, and many of the entries have ages associated with them. So I punted.
Name: First Name, Middle Name [Details not mentioned for privacy]
Birth year: 1940
That's all I gave it. Only 1 result in the Public Records Index. In the same town her mother died, and 30 miles from where her brother died. (Individually the first and middle names are fairly common, but not too many people use both.) Is it her?
If the town had a population of 1000, I wouldn't hesitate. However, it's Los Angeles, the second largest city in the United States. It could easily be a coincidence. But I have a name to research, and an address to which a letter could be sent. I'm not exactly sure what the letter would say....
If you are not ____(maiden name)____ I apologize for the inconvenience, and please discard this letter.
However, if you are...