Should we create a [regression-discontinuity] tag?

There are ~130 RD questions on the site (with some false positives) and it is a standard quasi-experimental inference method in economics and other fields. Does this volume merit its own tag?

• Please note that there exists discontinuity tag with 40 Qs. If you create [regression-discontinuity], you should probably check whether [discontinuity] is meaningfully different; perhaps most of these 40 threads can be moved to [regression-discontinuity] and the rest does not need to have this tag at all. In any case one needs to figure out what to do with [discontinuity] before creating [regression-discontinuity]. – amoeba says Reinstate Monica Oct 24 '17 at 11:15
• @gung I added the tag on one of the questions with a description. Once approved, I will start re-tagging the older questions. – Dimitriy V. Masterov Oct 26 '17 at 17:18
• Did we come to any conclusions about what to do w/ the [discontinuity] tag? Should we initiate another thread about that? (cc, @amoeba) – gung - Reinstate Monica Nov 1 '17 at 0:39
• @gung To be honest I don't think it's worth another Meta thread. The tag currently has only 22 threads left. My feeling is that it's a diverse collection of topics which makes this tag not very useful (if it all), especially given that some of these 22 could/should be retagged as [changepoint] anyway. I'd get rid of it. But it's not an awful tag; no big harm if it stays either. – amoeba says Reinstate Monica Nov 1 '17 at 0:56
• If we can come up w/ a useful, er, use for the tag, & can edit the excerpt to provide useful guidance, I'm fine w/ keeping it. If not, it would be better to remove it from all remaining threads & let it die, @amoeba. – gung - Reinstate Monica Nov 1 '17 at 1:01
• @gung Well, okay, I went over these threads and removed [discontinuity] from all of them, retagging as appropriate. It really didn't have any coherent meaning and wasn't useful. – amoeba says Reinstate Monica Nov 1 '17 at 11:33

I don't see why not. That is a perfectly valid topic. We have other, similar tags for methods used to infer causality from observational data, including:

As always, if you do create the tag, please add a good excerpt to guide usage, and preferably a good full wiki as well.

It seems we already have a tag with 40 threads (ht, @amoeba). Of those, 22 have both [regression] and [discontinuity] and certainly more than half are really about RD. There are also 17 threads with [regression] and "discontinuity", but without the tag. I think it would be better to have an explicit [r-d] tag specifically for RD. The term / idea of discontinuity is somewhat generic. It could cover RD, but could also be used for something like or something else (e.g., Is there a way to correct for continuity for the Shapiro-Wilk test?). If we did create a new tag for RD, the question then is what to do w/ [d]. My first thought would be to go through those 40 threads and properly retag them, leaving [d] only on those threads like the one just linked that are about other senses of discontinuity and that can't be given a more specific tag. Then we could edit the wiki excerpt to provide better usage guidance.

• Agreed, regression-discontinuity is a relevant methodology in the Econometrics literature. – deps_stats Oct 22 '17 at 22:20
• I upvoted several days ago, but now noticed that there exists discontinuity tag with 40 Qs. One would need to figure out what to do with it before creating [regression-discontinuity]. – amoeba says Reinstate Monica Oct 24 '17 at 11:16
• Re Update: I agree but I'd say that in that case it would be better to eliminate [d] altogether. I am not sure there is any useful (useful for a tag) meaning of "discontinuity" once we take [r-d] out of it. – amoeba says Reinstate Monica Oct 24 '17 at 13:27
• That's a viable option, @amoeba. I'm open to that. This was just my first thought. – gung - Reinstate Monica Oct 24 '17 at 13:43
• Personally, I prefer the [regression discontinuity] rather than [r-d] or [rdd]. I think there is still room for [discontinuity]. There seem to be some questions about detecting structural breaks and their ilk, and that seems qualitatively different that making use of one that is known to exist. – Dimitriy V. Masterov Oct 25 '17 at 1:02
• @DimitriyV.Masterov, "r-d" & "rdd" is just my shorthand b/c I'm too lazy to type "regression-discontinuity" each time. But I mean that the new tag should be [regression-discontinuity]. – gung - Reinstate Monica Oct 25 '17 at 1:15