I agree with Mr Dougherty, in a perfect world we would not want or need to do this. Unfortunately when you get patients in the ER, getting a correct spelling of their name is second to stopping the bleeding. I've been using probabilistic techniques for years - particularly with EMS (emergency medical services), where the patient may not even be able to give a name.

I found that once we get below .80 the matches are of variable use. But it depends on the fields you have to match with, and the discriminating power of each within the set.

Hyphenated last names (for example Nordberg vs Halbe-Nordberg) are the worst as they produce very weak matches, but the match is evident when human reviewed - hence the need for human intervention.