Find Instrumental Variables

node_instrumental tags instrumental variables given an exposure and outcome. ggdag_instrumental plots all instrumental variables. See dagitty::instrumentalVariables() for details.

node_instrumental(.dag, exposure = NULL, outcome = NULL, ...)

ggdag_instrumental(
  .tdy_dag,
  exposure = NULL,
  outcome = NULL,
  ...,
  node_size = 16,
  text_size = 3.88,
  label_size = text_size,
  text_col = "white",
  label_col = text_col,
  node = TRUE,
  stylized = FALSE,
  text = TRUE,
  use_labels = NULL
)

Arguments

.dag, .tdy_dag	input graph, an object of class tidy_dagitty or dagitty
exposure	character vector of length 1, name of exposure variable. Default is NULL, in which case it will check the input DAG for exposure.
outcome	character vector of length 1, name of exposure variable. Default is NULL, in which case it will check the input DAG for exposure.
...	additional arguments passed to tidy_dagitty()
node_size	size of DAG node
text_size	size of DAG text
label_size	size of label text
text_col	color of DAG text
label_col	color of label text
node	logical. Should nodes be included in the DAG?
stylized	logical. Should DAG nodes be stylized? If so, use geom_dag_nodes and if not use geom_dag_point
text	logical. Should text be included in the DAG?
use_labels	a string. Variable to use for geom_dag_repel_label(). Default is NULL.

Value

a tidy_dagitty with an instrumental column for instrumental variables or a ggplot

Examples

library(dagitty)

node_instrumental(dagitty("dag{ i->x->y; x<->y }"), "x", "y")
#> # A DAG with 3 nodes and 3 edges
#> #
#> # A tibble: 4 x 11
#>   name      x     y direction to     xend  yend circular instrumental_na…
#>   <chr> <dbl> <dbl> <fct>     <chr> <dbl> <dbl> <lgl>    <chr>           
#> 1 i      7.21  6.18 ->        x      7.22  5.02 FALSE    i               
#> 2 x      7.22  5.02 ->        y      7.22  4.13 FALSE    i               
#> 3 x      7.22  5.02 <->       y      7.22  4.13 FALSE    i               
#> 4 y      7.22  4.13 NA        NA    NA    NA    FALSE    i               
#> # … with 2 more variables: adjusted <fct>, instrumental <chr>
ggdag_instrumental(dagitty("dag{ i->x->y; i2->x->y; x<->y }"), "x", "y")