Identify instrumental variables for a given exposure-outcome pair.
Usage
query_instrumental(
.tdy_dag,
exposure = NULL,
outcome = NULL,
conditioned_on = NULL
)
Arguments
- .tdy_dag
A tidy_dagitty or dagitty object
- exposure
Character vector of exposure variable names. If NULL,
uses the exposure defined in the DAG.
- outcome
Character vector of outcome variable names. If NULL,
uses the outcome defined in the DAG.
- conditioned_on
Defunct. dagitty::instrumentalVariables() works out
the conditioning set an instrument requires on its own and reports it in
the conditioning_set and conditioned_on columns, so there is nothing
for this argument to do. Supplying it is an error.
Value
A tibble with columns:
instrument: The instrumental variable
exposure: The exposure variable
outcome: The outcome variable
conditioning_set: String representation of conditioning variables
conditioned_on: List column of required conditioning variables
Examples
library(ggdag)
dag <- dagify(
y ~ x + u,
x ~ z + u,
exposure = "x",
outcome = "y",
latent = "u"
)
query_instrumental(dag)
#> # A tibble: 1 × 5
#> instrument exposure outcome conditioning_set conditioned_on
#> <chr> <chr> <chr> <chr> <list>
#> 1 z x y {} <chr [0]>
