Types of Validity in Research

Validity is important to any type of research. Types include (but are NOT limited to!):

• External validity - the degree to which the research can be generalized to other settings. There are 2 types: population validity, and ecological validity
• Internal validity - the degree to which the research accurately follows cause and effect
• Criterion validity - the degree to which the research results concur with other research on the same construct to come to the same conclusions. An example of this might be whether GPA scores correlate to SAT scores.
• Content validity - the degree to which the research measures accurately the "content" associated with the construct studied. So, for instance, if a literacy test only looks at grammar, it is missing many different parts of the construct called "literacy" since literacy requires much more than just grammar!
• Construct validity - the degree to which the "construct" measures what it's supposed to measure. For instance, does IQ actually measure intelligence as it is supposed - or something else, such as test-taking proficiency or cultural understandings. An example of a problem with construct validity in the IQ test is that it is specific to the country/jurisdiction. The IQ tests in the US use imperial measurements (inches, feet, gallons) so a person in Canada might score poorly on such questions not because they do not know how to convert measurements, but because they are familiar with metric (not imperial) measurements
• Face validity - similar to content validity, face validity has to do with whether the research appears to measure what it is supposed to measure based on expert observers. A famous example of this would be the "tests" used during the Salem Witch Trials. The "test" of burning witches at the stake might have seemed to some at the time as valid, but we know now that it was seriously flawed.
• Predictive validity - the degree to which the research will predict certain types of results if similar research is done in the future. For example, are SAT scores predictive of academic performance in college?