The identification of average causal effects of a treatment in observational studies is typically based either on the unconfoundedness assumption or on the availability of an instrument. When available, instruments may also be used to test for the unconfoundedness assumption (exogeneity of the...

In March 2013, Lululemon Athletica removed its inventory of women's black yoga pants from its stores because recent shipments of the product were “too sheer.” For a company reliant on a reputation for quality, the news was devastating. Worse, the recall set off a series of PR related...