Establishing the internal validity of a study is based on a logical process. For a research report, the logical framework is provided by the report's structure. The methods section describes what ...

2. Internal validity Assess internal validity on basis of research design and operational procedures. Difference is most likely due to the treatment; proceed to next step. Difference is probably ...

Although a randomized controlled trial is generally accepted as the most effective way to assess clinical efficacy ... neither external nor internal validity appears to suffer significantly.