Question

List three reason why a study may be considered invalid

Answer 1

no evidence, no research, no explanation or no otherization 

Answer 2

1. Lack of Research: When a study does not fulfills the research method's requirements, it is not considered to be a valid one.
2. No Evidence: When researchers fails to provide a valid evidence of their findings then, such work is not be trusted and the study becomes invalid.
3. Biased opinions: A study, which follows all the process, provides evidence but is biased in one way or the other, then such study is also categorized as invalid.