Chapter 9: Theory of Reasoned Action/Theory of Planned Behavior and Integrated Behavioral Model
Measurement of Constructs
5 or 7 point scales
Bipolar or bidirectional scales (also known as semantic differential scales): unlikely / likely, disagree / agree, good / bad.
Unipolar or unidirectional scales: very little control / complete control, not at all worried / extremely worried.
Scoring from -3 to +3 such that:
Belief that behavior will result in a positive outcome contributes positively to measure.
Belief that behavior will result in negative outcome contributes negatively to measure.
Elicitation studies: studies conducted to identify and select the content for the construct measures.
Example: Before behavioral beliefs can be measured, the researcher must know what they are for the health behavior and population studied.
It is always important to pilot test your measures / instrument
Direct measurement refers to measurement on a major construct (example: attitude, subjective norms, perceived behavioral control). These are usually more strongly associated with outcomes than indirect measures. Demonstrate these associations before proceeding to indirect measures.
Indirect measurement refers to measurement on the minor constructs that comprise the major construct and then calculating these scores across the outcomes of the behavior.
major construct = attitude, indirect measurement measures
minor constructs = behavioral beliefs, evaluation of behavioral outcomes; calculation discussed later
It is important to show strong association between these measures and the major construct to ensure the appropriate beliefs were measured. If so demonstrated, these are of most interest.
Assess instrument reliability by test-retest reliability and/or internal consistency reliability.