These approaches more credibly identify causal effects than the above approaches that separately address the main types of possible bias.
We therefore complement the above analysis by two natural experiments that more credibly identify exogenous variation in skills that is independent of other influences such as family background or health limitations.
Those who apply little discount for steroids use may credibly claim to identify 15 or more qualified candidates, and even those who do not may have to drop one or two names that they otherwise see as worthy.
In our review, we identified no publications that credibly challenge long-standing conclusions that increases in the concentration of airborne pollutants would increase morbidity and premature mortality.
But the six Illinois dioceses have so far only publicly identified 185 clergy members as having been "credibly" accused of sexual abuse.
Indeed, Catholicism had already entered an era when thousands of priests would be, in its own judgment "credibly accused" and tens of thousands of children would be identified as victims.
However, the public disclosure of health information can only be done if it is credibly de-identified.
Most of the students were still in their teens, in their first semester at the school, and came from impoverished communities that a majority of Mexicans can identify with; they can't credibly be criminalized as "guerrillas" or "narcos".
