![]() Visit a store with the current service owner.Stata resources are included with the linked paper. test multiple matching protocols and find that automated comparison techniques compare favorably to human matching in a variety of circumstances. This has been evaluated in the economics literature for historical record linkage. Data preparation to create this usually involves joining a single master variable to the ID variables in the using dataset.Ī number of other commands and approaches eist for this problem. strgroup works within a single dataset.This command calculates the difference between strings and uses a user-specified threshold to create groups/matches. You will need to type net install strgroup to get this command.The results from matchit can be merged by joinby or merge to the using or master datasets, but matchit does not function like a merge.All of these provide more than one likely match, which can be used to determine a second best guess. matchit has multiple matching algorithms that are explained in the helpfile.You can match multiple columns sequentially and average or weight the probabilities to match on multiple string columns. matchit only matches single variables to generate a probability score between those variables.This is installed by typing net install dm0082 to install the entire package. There is a second reclink2 command that improves on the reclink command and adds many-to-one matching.When using reclink, tempfiles can be especially helpful, since you will likely need to be jumping back and forth between files to change variables names, and changing names simply for the period of matching might be one of the easiest ways of ensuring you’re preserving the original versions of variable names in your dataset. If idusing() and idmaster() have the same variable names, matches might not happen properly.The two datasets shouldn’t share any variable names except for the variables for matching. reclink will not merge in values of shared variables from the using dataset without warning the user.If this is the case, _merge match U* should be right. The variable specified to idusing() should never be in the master dataset.Each bullet below describes a problem along with the attempted solutions and whether they succeeded. reclink is has some well known issues: Previous RAs have run into the following issues.reclink also supports string matching, so, for example, you can try using string variables in the linkage even if the variables aren’t perfectly clean. For example, two numeric ages of 25 and 26 are a closer match than 35 and 65. Instead of a single unique ID, you specify one or more variables that reclink assess for similarity.All are user written and can be installed using ssc install : reclink There are a few commands that can help with fuzzy mergeing in Stata. 0.2 Jaro-winkler distance) where the match is considered successful, after which records need to be manually matched. Matching review – matches need to be reviewed to decide the point (e.g.Probabilistic matching – the fuzzy matching function estimates a probability that an observation in the master data one matches to an observation in the using data.Based on the data this can include common phrases such as titles (e.g. String cleaning – prepare the match data by standardizing spaces, capitalization, removing special characters.Usually fuzzy matching consists of three steps: Exact matching is almost always preferred if it’s posssible. ![]() If you are thinking about using one of these commands, check with your manager to identify alternatives as fuzzy mergeing’s match rate is usually much less than exact matching. Commands that use this type of algorithms will typically give out probabilities of matches and should only be used when exact matching is not an option. Fuzzy merging, also called fuzzy matching, is a solution in that case.įuzzy matching refers to the technique of finding strings that approximately match or are the most likely to be similar in two sets of comparisons, rather than exactly matching. ![]() Small numbers of mismatchs can be manually matchin But in many cases the amount of data may make this impossible. For data where names are machine entered, removing obvious sources of mismatches (spaces, capital letters, etc.) may resolve this problem. ![]() However, this approach is often inaccurate: small misspellings in these variables can easily result in mismatches. The most obvious way to do this is to try and match on names or other string variables. Sometimes, however, no unique identifier was collected, and you’re left searching for alternative ways to link two datasets. Usually when you merge, you have a unique ID - or at least enough of one that you can salvage.
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