RFC: implemented StatsModels.lrtest , fixes #683

[ajinkya-k]

Issue #683 talks about adding StatsModels.lrtest. If I understood the code correctly, the only thing that was different from likelihoodratiotest was checking if models are nested. I implemented an StatsModels.isnested function that takes any number of MixedModels, and used that to implement StatsModels.lrtest

Did behavior change? Did you add need features? If so, please update NEWS.md

• add entry in NEWS.md
• after opening this PR, add a reference and run docs/NEWS-update.jl to update the cross-references.

Should we release your changes right away? If so, bump the version:

• I've bumped the version appropriately

[ajinkya-k]

@dmbates let me know what you think

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 9 lines in your changes missing coverage. Please review.

Project coverage is 97.08%. Comparing base (7b37191) to head (c9e6ed9).

Files with missing lines	Patch %	Lines
src/likelihoodratiotest.jl	0.00%	9 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #811      +/-   ##
==========================================
- Coverage   97.33%   97.08%   -0.26%     
==========================================
  Files          36       36              
  Lines        3490     3499       +9     
==========================================
  Hits         3397     3397              
- Misses         93      102       +9     

Flag	Coverage Δ
current	96.74% <0.00%> (-0.25%)	⬇️
minimum	97.08% <0.00%> (-0.26%)	⬇️
nightly	96.66% <0.00%> (-0.26%)	⬇️

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[palday]

@ajinkya-k this shouldn't be necessary if StatsModels is loaded: lrtest is a generic function. Using current releases:

julia> using MixedModels; using StatsModels: lrtest; using MixedModels: dataset

julia> fm0 = lmm(@formula(reaction ~ 1 + (1|subj)), dataset(:sleepstudy));

julia> fm1 = lmm(@formula(reaction ~ 1 + days + (1 + days|subj)), dataset(:sleepstudy));

julia> lrtest(fm0, fm1)
Likelihood-ratio test: 2 models fitted on 180 observations
─────────────────────────────────────────────────────────
     DOF  ΔDOF     LogLik   Deviance     Chisq  p(>Chisq)
─────────────────────────────────────────────────────────
[1]    3        -955.2705  1910.5411                     
[2]    6     3  -875.9697  1751.9393  158.6017     <1e-33
─────────────────────────────────────────────────────────

[ajinkya-k]

interesting! in that case the issue can also be closed right?

[palday]

interesting! in that case the issue can also be closed right?

The fix for the original issue is more like #814 😄