piecewiseSEM: Exploring Nature’s Complexity through Statistics

Post provided by Jonathan S. Lefcheck

Nature is complicated. As a scientist, you might say, “Well, duh,” but as students of nature, this complexity is probably the single greatest challenge we must face in trying to dissect the hows and whys of the natural world.

History is a Set of Lies Agreed Upon: Moving beyond ANOVA

For a long time, we tried to strip this complexity away by conducting very controlled experiments adhering to rigid designs. The ‘two-way fully-crossed analysis of variance’ will be familiar to anyone who has taken even the most basic stats class, because, for many decades, it was the gold standard for any experiment.

It might be tough to manipulate this whole reef.

The problem is: the real world doesn’t adhere to an ANOVA design. By this, I mean that by their very nature, manipulative experiments are artificial. It’s hard—if not impossible—to manipulate an entire forest or a coral reef, and as such, we retreat to more tractable, smaller investigations. There is certainly a lot of value in determining whether the phenomenon can occur, but these tightly regulated designs say nothing about whether they are likely to occur, particularly at the scales most relevant to humanity.

To get at the latter point, we must leave the safety of the greenhouse. However, our trusty ANOVA toolbox isn’t very useful anymore, because real-world data often violate the most basic statistical assumptions, not to mention the presence of numerous additional influences that may drive spurious relationships. Continue reading

2016 Robert May Prize Winner: Gabriella Leighton

The Robert May Prize is awarded annually for the best paper published in Methods in Ecology and Evolution by an Early Career Researcher. We’re delighted to announce that the 2016 winner is Gabriella Leighton, for her article ‘Just Google it: assessing the use of Google Images to describe geographical variation in visible traits of organisms.

‘Just Google it’ marks an important step in converting ecology to an armchair science. Many species (e.g. owls, hawks, bears) are difficult, time-consuming, expensive and even dangerous to observe. It would be a lot easier if we didn’t have to spend time, energy and risk lives having to observe organisms in the field! Continue reading

Issue 7.5

Issue 7.5 is now online!

The May issue of Methods is now online!

This month’s issue contains two Applications articles and two Open Access articles, all of which are freely available.

piecewiseSEM: A practical implementation of confirmatory path analysis for the R programming language. This package extends the method to all current (generalized) linear, (phylogenetic) least-square, and mixed effects models, relying on familiar R syntax. The article also includes two worked examples.

 RPANDA: An R package that implements model-free and model-based phylogenetic comparative methods for macroevolutionary analyses. It can be used to:

  1. Characterize phylogenetic trees by plotting their spectral density profiles
  2. Compare trees and cluster them according to their similarities
  3. Identify and plot distinct branching patterns within trees
  4. Compare the fit of alternative diversification models to phylogenetic trees
  5. Estimate rates of speciation and extinction
  6. Estimate and plot how these rates have varied with time and environmental variables
  7. Deduce and plot estimates of species richness through geological time. Continue reading