We have augmented-dickey-fuller tag with 148 questions.
There are 407 questions I find when searching for ADF (Augmented Dickey Fuller).
There are 174 questions I find when searching for KPSS (Kwiatkowski-Phillips-Schmidt-Shin).
Both the ADF Test as well as the KPSS test are tests which test whether a time series is stationary. The Null hypothesis of the ADF test is that there is a Unit root. The Null hypothesis of the KPSS Tests is that the time series is stationary.
As KPSS test more or less the complement to the ADF test I propose to create a tag for the KPSS test as well.
More generally we could discuss the same issue for other tests, e.g. the Phillips-Perron Test.