[R-sig-ME] Crossed and nested factors in experimental designs: Are there any flowcharts for decision making?

[Ben Bolker]

On 14-11-14 05:21 AM, Mehdi Abedi wrote:
> Dear all,
> 
> I am following your nice discussion in this group. Considering your high
> level discussion in this group i was not sure to ask basic problems in the
> mailing list!, therefore, i asked this question in researchgate.
> 
> I think several researchers have this kind of question which your guidance
> can also help them using mixed models in their researches. I can imagine
> that teaching advanced statistic with simple language is not easy. However
> in addition to advanced statistic books and codes, introducing experimental
> design and their link to mixed models using simple codes would be valuable
> as well.
> 
> It would be my pleasure to have your suggestion here or in this link:
> 
> Warm regards
> 
> Mehdi:
> 
> https://www.researchgate.net/post/With_regards_to_crossed_and_nested_factors_in_experimental_designs_Are_there_any_flowcharts_for_decision_making
> 
> Ecological researches mainly have complicated statistical design. Mixed
> models can test complicated designs with different crossed or nested
> factors. For instance lme4 and nlme could be used in R. However, still
> decision about statistical design is complicated for most researchers.
> 
> Mixed models are quit an advanced method for most researchers and recent
> publications still use simple statistical designs. For instance most
> publications in high ranked journals related to plant ecophysiology and
> seed researches still apply only factorial design for the statistical
> analysis and not mixed models including random and fixed factors.
> 
> Could you recommend some references or lectures introducing nested, crossed
> design with simple examples and simple codes in R?. I mean some simple
> explanation without details which start from simple design to complicated
> design like http://conjugateprior.org/2013/01/formulae-in-r-anova/
> <https://www.researchgate.net/go.Deref.html?url=http%3A%2F%2Fconjugateprior.org%2F2013%2F01%2Fformulae-in-r-anova%2F>
> 
> Graphical designs showing these crossed and nested would also be useful.
> This information would be very helpful for both teachers and researchers
> for application correct statistical analysis.

  It's pretty basic, but I like the section in Gotelli and Ellison's
_Primer of Ecological Statistics_.  They don't really get as far as
crossed random effects, but they do discuss nested, randomized block,
split-plot, and factorial (i.e. _crossed fixed effect_) designs.

  Ben Bolker



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