Feldman–Hájek theorem
Feldman-Hájek theorem is about understanding how two different kinds of data – observed data and potential data – relate to each other. Observed data is the data we have seen, like measurements we have taken or things we have counted. Potential data is data that we think exists, but don't actually measure.
The theorem says that when we have both kinds of data, any conclusions that we make using only the observed data will also apply to the potential data. In other words, what we can say about what we have seen also applies to what we haven't seen.
The theorem says that when we have both kinds of data, any conclusions that we make using only the observed data will also apply to the potential data. In other words, what we can say about what we have seen also applies to what we haven't seen.