AFAIK, "nested" can refer (and this tag is being used to refer) to various conceptually different things that have little to do with each other:
- Nested data / nested experimental design (nested factors in ANOVA, nested random effects in mixed models, etc.)
- Nested models (e.g. doing LR test on two nested models)
- Nested cross-validation
Update April 2016: I looked through the last 50 threads tagged with [nested]. 39 are about nested data (split ~50:50 between ANOVA and mixed models); 1 is about nested models; 10 are about nested cross-validation. Among the [non-nested] threads, most seem to be about nested models.
I suggest to split these two tags into three new tags, corresponding to the above categories.
[nested-data]be an okay name for nested anova/lmer stuff? We could have nested-anova, nested-random-effect, nested-factor as synonyms. There is also a
[multilevel-analysis]tag, but people asking about nested anova do not usually use this terminology...
[nested-models]would do, wouldn't it?
Do we need
[nested-cross-validation]tag, or can we retag these threads to
[cross-validation]and that's it?