DF between-within

[strengejacke]

http://de.saswiki.org/images/d/d4/11.KSFE-2007-Buescher-Analyse_longitudinaler_Daten.pdf

[mattansb]

Ich nicht spreche Deutsch 🤷‍♂️ Was ist das? (Hope I got that right?)

[strengejacke]

I haven't found a good resource quickly, the idea came up when reading this thread:
https://stats.stackexchange.com/q/443241/54740

[strengejacke]

http://www2.sas.com/proceedings/sugi26/p262-26.pdf

[Generalized]

Also, you may find this one informative:
Li, Peng & Redden, David. (2015). Comparing denominator degrees of freedom approximations for the generalized linear mixed model in analyzing binary outcome in small sample cluster-randomized trials. BMC medical research methodology. 15. 38. 10.1186/s12874-015-0026-x.

https://www.researchgate.net/publication/275363360_Comparing_denominator_degrees_of_freedom_approximations_for_the_generalized_linear_mixed_model_in_analyzing_binary_outcome_in_small_sample_cluster-randomized_trials/stats

Currently, in R, only the containment method seems to be implemented (glmmPQL, nlme). In the repeated observations, especially in longitudinal trials, the between-within DF is often preferred as the last-resort option, if K-R or Satterthwaite cannot be used.

[strengejacke]

Thanks for the hint to the paper. I'm not sure how the DDF-B-W are calculated. The paper simply states K - rank[x], but I'm not sure where rank[x] refers to.

[strengejacke]

Any SAS-Users here that can provide the output of some toy example that can be reproduced in R, so I can check the implementation of dof_betwithin()? I think in particular for nested random effects, the computation might differ...

[strengejacke]

@bwiernik maybe you could also give some input here?

[bwiernik]

rank(x) refers to rank of the fixed effects design matrix

[bwiernik]

The between-within method was derived for repeated measures (fixed effects) designs with various error structures, not for random effects or mixed effects designs. So it doesn't pay any attention to the random effects design matrix