I confess that I made a new tag: identity
. A search of 'identity' on the main site yielded 1110 questions, and being able to label something as an identity and search for it is a good thing. Identities are extremely important when writing new statistical density functions, and can disguise two expressions that are equal, but not recognizably so. When I develop new pdf's, CDF's, expected values, and the like, I keep a separate list of useful identities that makes it possible for me to work through those statistical formulas.
Identities are important to note explicitly because if you do not know them by heart, or at least recognize that they might exist for a function, you will be stuck completely doing integration (e.g., CDF finding), simplification, expectation, proofs, and other mathematical steps. Almost any class of functions has numerous identities the existence of which should be known to do novel statistical development work. For example, hyperbolic functions have numerous identities.
So, question is, what do you think about identity
as a new tag? See Understanding an Estimator Identity as an example.
identity
to be an unusually important concept, nor do you differentiateidentity
from the other search terms you mockingly put forward. I do not intend to createequality
,inequality
,formula
, orexpression
. The importance of identities has become more apparent to me the more I have explored hitherto uncharacterized distributions and physically relevant novel statistical physics. I would suggest that if you were to do likewise, you would understand better why I hold identities in high esteem. $\endgroup$ – Carl Nov 8 '16 at 16:31identity
off the Meta site $\endgroup$ – Carl Nov 8 '16 at 16:50[identity]
tag. One thing that might help is if you made a tag excerpt for it. It isn't remotely clear to me what the tag is supposed to be for, or how to decide if it picks out anything of value about a question. Is the idea that it should be on any thread that includes an equals sign? $\endgroup$ – gung - Reinstate Monica Nov 8 '16 at 21:18[identity]
on questions like 'how to add an ID variable to my panel data since it's in long format', or some such. $\endgroup$ – gung - Reinstate Monica Nov 9 '16 at 22:05