semEff provides functionality to automatically calculate
direct, indirect, and total effects for ‘piecewise’ structural equation
models, comprising lists of fitted models representing structured
equations (Lefcheck, 2016; Shipley, 2000, 2009). Confidence intervals
are provided via bootstrapping.
Currently supported model classes are "lm",
"glm", "lmerMod", "glmerMod",
"lmerModLmerTest", "gls", and
"betareg".
You can install the released version of semEff from CRAN with:
install.packages("semEff")And the development version from GitHub with:
devtools::install_github("murphymv/semEff@dev")The primary function is semEff(),
which returns an object of class "semEff" with associated
print() and summary() methods. Everything can
technically be accomplished in a single call to semEff();
however, since bootstrapping is employed to generate resamples for
confidence intervals (via bootEff()),
it is usually preferable to save these estimates separately prior to
calling semEff() – allowing more flexibility and saving
time if/when recalling the function.
Package functions are well-documented and most include some short examples. In addition, see the following vignettes for some longer demonstrations:
Analysing direct vs. indirect effects of landscape ___location on plant species richness
Predicting and plotting indirect effects of degree days to bud burst on tree growth
Lefcheck, J. S. (2016). piecewiseSEM: Piecewise structural equation modelling in R for ecology, evolution, and systematics. Methods in Ecology and Evolution, 7(5), 573–579. doi:10/f8s8rb
Shipley, B. (2000). A New Inferential Test for Path Models Based on Directed Acyclic Graphs. Structural Equation Modeling: A Multidisciplinary Journal, 7(2), 206–218. doi:10/cqm32d
Shipley, B. (2009). Confirmatory path analysis in a generalized multilevel context. Ecology, 90(2), 363–368. doi:10/bqd43d