Survey Design Class 02 STAT 472 VALIDITY It

Survey Design Class 02 STAT 472

VALIDITY � It is a true measure � Measurement Validity is the degree of fit between a construct and indicators of it. � It refers to how well the conceptual and operational definitions mesh with each others � The better the fit the greater the measurement

� When a researcher says that indicator is valid, it is valid for a particular purpose and definition. But less valid or invalid for others

EXAMPLE � Questions about feelings toward school � Valid: for measuring morale among � Invalid: for measuring morale of teachers police officers

TYPES OF MEASUREMENT VALIDITY � (1)Face Validity It is a judgment by the scientific community that the indicator really measures the construct

(2) CONTENT VALIDITY � Special � type of face validity is the full content of a definition represented in a measure?

CONTENT VALIDITY INVOLVES THREE STEPS: (1) Specify the content in a construct’s definition (2) Sample from all areas of the definition (3) Develop an indicator that taps all of the various parts of the definition.

(3) CRITERION VALIDITY � The validity of an indicator is verified by comparing it by another measure of the same construct in which a researcher has confidence

TWO KINDS OF CRITERION VALIDITY � (a) Concurrent: an indicator must be associated with preexisting indicator that is judged to be valid. Example: Create a new test to measure intelligence.

� (b) Predictive: Indicator predicts future events that are logically related to construct. Example: the Scholastic Aptitude Test (SAT): to measure the ability of a student in college; if the SAT has high predictive validity, the students who get high SAT scores will subsequently do well in college.

(4) CONSTRUCT VALIDITY � For � It measure with multiple indicators. has two kinds: (a) Convergent: Means that multiple measure of the same construct operate in similar ways

� (b) Discriminant: (Divergent Validity) It means the indicators of one construct are negatively associated with opposing construct.

OTHER USES OF THE TERM VALIDITY � (1) Internal Validity: means there are no errors internal to the design of the research project High internal validity means there are few errors

� (2) External Validity: It is the ability to generalize findings from a specific setting and small group to board range of setting and people High external validity means the results can be generalized to many situations and many groups of people.

� Statistical Validity: Means the correct statistical procedure is chosen and its assumptions are fully met