The participants were not informed of the content of the experiment until after they had arrived at the testing site, so self-selection based on environmental attitudes or architectural preferences was eliminated.
Given the forces of self-selection , they worried that those who were relatively disadvantaged members of society and driven by economic necessity would fill the lower ranks of the all-volunteer force.
This self-selection could occur prior to hire as a result of a job candidate's suspicion about harmful exposures, or after hire as a result of first-hand experience with work-related respiratory problems.
It allows for fine-tuning and self-selection of migration flows, yielding far better results than even the most well-meaning bureaucrats could ever achieve.
In the general population from Spain, a higher asthma risk was observed in former cleaners than in current cleaners, suggesting self-selection related to exposure.
This self-selection does represent a potential bias, since participants have been self-selected on the basis of interest and, possibly, prior experience.
Entrance into most preparation programs has been determined by self-selection , with half-hearted screening and little outreach to talented individuals.
The first process, self-selection , was created by internal motivational states and/or external incentives that disposed some people to volunteer for treatment.
These study demands may have increased the potential for self-selection such that participants' interest on their own health and time availability may have created a fairly homogeneous sample.
In particular, we estimate the effect of herbicide-tolerant soybeans on herbicide use, crop yields, and farm profits using an econometric model that corrects for self-selection and simultaneity.