Before revision:  This is achieved by a localized version of the first test, using only individuals with propensity score close to one . Although the second step requires `identification at infinity' , we can allow for cases of irregular identification.
After revision:  This is achieved by a localized version of the first test, using only individuals with propensity score close to one , this test relies on an `identification at infinity' , we can allow for cases of irregular identification.