Dealing with aliases in FastLink about fastlink HOT 1 OPEN

Disclaimer: I am a fastLink user, not a fastLink developer

The accuracy of the linkage results will greatly improve if you have more and better linkage variables such as Social Security Number. But I would like to focus my reply comments on fastLink.

I am not aware of an always-best answer. The fastLink article (2019, page 362) found no distinguishable difference between a one-to-one match and a one-to-many match. Therefore, personally, I almost always use a one-to-one match. But in some other cases it is better to de-duplicate before doing a record linkage. It depends on the context, for example what you know about the data, how much time you have for doing the record linkage, including a manual ("clerical") review of uncertain record pairs, and what is an acceptable threshold matching probability.

Regardless, I recommend to pay attention to the de-duplication results -- especially if you main concern is wrong matches (false positives) rather than missed matches (false negatives). The default is dedupe.matches = TRUE , which has two algorithms: one default "greedy" (faster but simple) and one optional "linear programming" (slower but recommended for accuracy). If you have a large linkage, then the default de-duplication algorithm might not be accurate enough and the optional algorithm might be too slow. In that situation, you can still get good results by running fastLink a second time by changing to dedupe.matches = FALSE. This will give you two different results with the only difference being the de-duplication. Then, you can do a manual review of those uncertain record pairs.

Also, fastLink does not require exact matching of an individual linkage variable. In fact, you are encouraged to try out different and more flexible matching options depending on the data and what you know about the data. A few examples are "Jaro-Winkler" and "Double Metaphone" of name, and using age instead of dob.

In summary, the fastLink defaults are usually good enough that there is nothing special that you have to do -- except maybe if you need blocking and a confusion table. If you will have any such issues, see my comment in issue #63. The fastLink developers are working on updating fastLink for easier, faster, and more accurate results, so stay tuned!

from fastlink.