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