Having face validity does not mean that a test really measures what the researcher intends to measure, but only in the judgment of raters that it appears to do so. It should be noted that the term face validity should be avoided when the rating is done by an “expert,” as content validity is more appropriate. The face validity of a test can be considered a robust construct only if a reasonable level of agreement exists among raters. Finally, the researcher could use members of the general public with an interest in the test (e.g., parents of testees, politicians, teachers, etc.). For example, individuals who actually take the test would be well placed to judge its face validity.Īlso, people who work with the test could offer their opinion (e.g., employers, university administrators, employers).
It is important to select suitable people to rate a test (e.g., questionnaire, interview, IQ test, etc.).
Internal validity can be improved by controlling extraneous variables, using standardized instructions, counterbalancing, and eliminating demand characteristics and investigator effects.Įxternal validity refers to the extent to which the results of a study can be generalized to other settings (ecological validity), other people (population validity), and over time (historical validity).Įxternal validity can be improved by setting experiments in a more natural setting and using random sampling to select participants. In other words, there is a causal relationship between the independent and dependent variables. Internal validity refers to whether the effects observed in a study are due to the manipulation of the independent variable and not some other factor.
Internal and External Validity In Research
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