Explain and identify threats to internal and external validity in research methods?

here's the links you need:





internal: http://en.wikipedia.org/wiki/Internal_va...





external: http://en.wikipedia.org/wiki/External_Va...





good luck

Explain and identify threats to internal and external validity in research methods?
"One major source of confounding arises from non-random patterns in the membership of participants in the study, or within groups in the study. This can affect internal and external validity in a variety of ways, none of which are necessarily predictable. It is often only after doing a great deal of work that we discover that some glitch in our procedures or some oversight has rendered our results uninterpretable."

dog teeth