For instance, a match on a date of birth column lends a greater weight of evidence in favour of a match than a match on first name (since dob has higher cardinality).

The method is also able to estimate weights for fuzzy matches (how much evidence in favour of a match is close match on dob with one character difference), and also how much evidence against a match a mismatch is.

For instance, if you have very high data quality on gender, then a match on gender doesn't tell you much, but a mismatch on gender is quite strong evidence against the idea two records match.

I have a blog post here that delves into this a bit more: https://www.robinlinacre.com/fellegi_sunter_accuracy/