Placebo-outcome test — ssb_placebo • ssBartik

Runs the *same* shift-share IV but on an outcome that the treatment should not move (a placebo). A coefficient far from zero signals that the design is picking up something other than the intended channel. This is distinct from [ssb_pretrend()], which regresses a *pre-period* outcome on the instrument (reduced form) to look for differential pre-trends.

Usage

ssb_placebo(
  design,
  placebo_y,
  methods = c("ehw", "cluster", "akm"),
  level = 0.95
)

Arguments

design: An [ssb_design()] object.
placebo_y: Column name of the placebo outcome in `data`.
methods: Standard-error methods (see [ssb_estimate()]).
level: Confidence level.

Value

An `ssb_estimate` for the placebo outcome.