There are serious issues with the internal validity of these studies as well. (educationnext.org)
· Delay or suspend any implementation of EPA's carbon dioxide and other regulations, until relevant questions are answered, and genuine evidence - based science is restored to the regulatory process — and used to evaluate the honesty and validity of studies used to justify the regulations. (townhall.com)
However, purposive selection of study site does leave a question on the external validity of the study for whole Nepal. (frontiersin.org)