**Efficient Least Squares for Estimating Total Causal
Effects**

`eff2`

is an `R`

package for estimating a total
causal effect from observational data under linearity and causal
sufficiency (no unobserved confounding, no selection bias). It can
consistently estimate any identified effect, including single and
multiple treatment variables. Moreover, the resulting estimate has the
minimal asymptotic covariance (and hence shortest confidence intervals)
among all estimators that are based on the sample second moment.

From CRAN:

`install.packages("eff2")`

Alternatively, the package can be installed from GitHub.

```
# install.packages("devtools")
# install.packages("rmarkdown")
# install.packages("qgraph")
::install_github("richardkwo/eff2", build_vignettes = TRUE) devtools
```

In case of problem, first make sure dependency pcalg is properly
installed. Several packages required by `pcalg`

are removed
from CRAN and have to be installed from BioConductor:

```
if (!requireNamespace("BiocManager", quietly = TRUE))
install.packages("BiocManager")
::install("graph")
BiocManager::install("RBGL") BiocManager
```

For a quick start, check out the vignette:

`vignette("eff2-doc")`

Guo, F. Richard, and Emilija Perković. “Efficient Least Squares for
Estimating Total Effects under Linearity and Causal Sufficiency.” *arXiv preprint
arXiv:2008.03481* (2020).