TRA and TPB measures can use either 5- or 7-point scales. A person’s behavioral be-
liefs about the likelihood that performance of the behavior will result in certain out-
comes are measured on bipolar “unlikely-likely” or “disagree-agree” scales. Evaluations
of each outcome are measured on bipolar “good-bad” scales. For example, one out-
come of “my quitting smoking” may be that this “will cause me to gain weight.” A
person’s behavioral belief about this outcome is measured by having him rate the like-
lihood that “my quitting smoking will cause me to gain weight.” The person’s eval-
uation of this outcome is measured by having him rate the degree to which “my gaining
weight” is good versus bad. These behavioral belief and evaluation ratings are usu-
ally scored from
−
3 to
+
3, capturing the psychology of double negatives, where a be-
lief that a behavior will
not
result in a negative outcome contributes positively to
the person’s attitude. An “indirect measure” of the person’s attitude toward per-
forming the behavior is computed by first multiplying her behavioral belief concern-
ing each outcome by her corresponding outcome evaluation ratings and then summing
these product scores across all outcomes of the behavior.