Dear all,
I want to estimate standardized effect size (SES) for three organism groups
that have been quantified in different ways at each site.
According to the SI in Kraft et al. (2011) Disentangling the Drivers of β
Diversity Along Latitudinal and Elevational Gradients. Science 333 (6050):
1755-1758
âThe β deviations therefore represent a standard effect size, with positive
values indicating more β-diversity than expected, and negative values
indicating less β-diversity than expected under the null model.â
Zhou et al. (in press) Stochasticity, succession, and environmental
perturbations in a fluidic ecosystem. PNAS.
also present estimates of the standard error of SES.
The help ?oecosimu (vegan library) describe the z-value of the
oecosimu-statistic based on simulation as SES.
I now wonder, does the Kraft et al. (2011) definition of SES hold also for the
SES calculated using oecosimu()? Thus, oecosimu() may report negative z?
The code that Kraft et al. provide randomly assign individuals to the plots.
I want to estimate SES for spiders, plants and fungi. At each site, the number
of individuals of each species spider have been counted, the cover of each
plant species have been recorded and the biomass of each fungal species have
been measured.
Is oecosimu() appropriate for estimating SES for these three organism groups?
If not, what do you suggest?
Literature suggestions where estimators of SES is discussed is most welcome.
Cheers,
Tord
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