some questions about matchit command

[Hualin Chl]

I use “matchit” command in stata to match two variables from two files. The whole command is " matchit id1 name using "xxx.dta" ,idusing(id2) txtusing
(name2) override". But before using matchit, I have nearly 20000 observations, the command runs successively, but after matching, I lose all my observations with no reasons ! This confuses me quite a lot..

[Justin Niakamal]

It's possible that the threshold for matchit (from SSC) is not met. From the helpfile:

threshold(num) Lowest similarity scores to be kept in final results. Default is num = .5.

You might consider starting by including thres(.01) as an option to see the similarity score between the matches.

[Hualin Chl]

thank u so much！ this truly helps me a lot！I have solved my problem by taking your suggestion.