CS235 Lecture Notes - Criterion Validity, Face Validity

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Published on 16 Apr 2013
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What is validity and what different forms of it exist?
Validity refers to the truth-value of a research project. How can we say whether
the reported results are true?
Measurement validity: measuring what you say you are measuring
Face validity: the degree to which measures (ex. Questions on a questionnaire)
successfully indicate concepts.
Criterion validity: comparing the results of questions with established indicators of
the same concept. Ex. Comparing the results of an interview survey of people’s
health status with the results of a doctor’s examination
- If the results differ from the doctor’s assessment the interview would be
judged to have poor validity
Construct validity: evaluates a measure according to how well it conforms to
expectations derived from theory
Ex. If health status is related to social class we would expect our measure of health
status to give different results for people from different social classes.
Internal Validity: the extent to which causal statements are supported by the
study.
External Validity: the extent to which findings can be generalized to populations or
other settings.
How does validity differ from reliability?
- Reliability has to deal with replicability. Reliability concerns the consistency
with which research procedures deliver their results.
Can a study be reliable without it being valid? Explain.
- Yes, you could have the same results over and over again but the project was
not valid.
- Why might it not be valid? It may not have measurement, internal or external
validity.
How might one ensure that the data collected for a study be valid?
- Triangulation
- Data: involves using diverse data so that one seeks out instances of a
phenomenon in several different settings, at different points in time or space.
- Investigator: involves team research; with multiple observers in the field
engaging in continuing discussion of their points of difference and similarity,
personal biases reduced.
- Theory: suggest that researchers approach data with several hypotheses in
mind to see how each fares in relation to the data.
- Methodological: e.g. Ethnolographic observation with interviews; mixing
quantitative and qualitative methods in a study.

Document Summary

Validity refers to the truth-value of a research project. Measurement validity: measuring what you say you are measuring. Face validity: the degree to which measures (ex. Criterion validity: comparing the results of questions with established indicators of the same concept. Comparing the results of an interview survey of people"s health status with the results of a doctor"s examination. If the results differ from the doctor"s assessment the interview would be judged to have poor validity. Construct validity: evaluates a measure according to how well it conforms to expectations derived from theory. If health status is related to social class we would expect our measure of health status to give different results for people from different social classes. Internal validity: the extent to which causal statements are supported by the study. External validity: the extent to which findings can be generalized to populations or other settings. Reliability concerns the consistency with which research procedures deliver their results.