Application of Behavior Change Theory to the Development

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BEHAVIOR CHANGE THEORY
The study’s outcome measures were the number of collisions and convictions in the
year following a subject’s assignment to a treatment group. Adjusted rates were used in
order to disregard differences in subsequent driving records attributable to age, gender,
prior convictions, and other relevant factors. The fact that some of these attributes
differed among groups casts doubt on the randomness of the selection process.
The adjusted collision rates for males, females, and both genders combined in the
warning letter group were determined to be no different from those of the control
group during the year subsequent to the subjects’ selection. Subsequent adjusted
conviction rates for both males and combined genders in the warning letter group were
found to be significantly different from those of the control group but the rates for
females affirmed the null hypothesis.
McBride and Peck, 1970
RATINGS:
Design Quality: 16/24
Standard Letter: 6/33
High Threat/High Intimacy: 18/33
High Threat/Low Intimacy: 10/33
Low Threat/High Intimacy: 24/33
Low Threat/Low Intimacy: 24/33
The importance of this pioneering effort to evaluate the effectiveness of the specific
elements of warning letters to catalyze quantum change in negligent operators is
monumental. At the time this study was published, only Kaestner, et al. (1965, 1967)
had studied the impact of warning letter components (McBride & Peck, 1970).
However, this study elevated the rigor associated with the approach.
As early as 1969, more than 100,000 negligent operators were involved in some form of
postlicensing control action each year in California. The general procedure was to
increase the intensity of the treatments as a function of driver recidivism. However,
these authors recognized the wisdom of improving warning letter treatments as a
means of reducing the need for increasingly stringent and expensive alternative
treatments. Their rationale was simple: a letter contact is less expensive than a meeting;
a large population of negligent operators can be easily contacted; it may be possible to
make a letter as effective as a meeting, and; a letter can reach negligent operators before
there is a need to resort to more punitive measures. Naturally, the success of this
strategy would depend upon the identification of letter components with the power to
increase the effectiveness of the letter treatments.
From November 1966 through January 1967, 18,000 negligent operators were selected
from the central driver record files at the California Department of Motor Vehicles, and
randomly assigned to one of four treatment conditions based on the fourth and fifth
digits of the eight digit driver license number. However, the procedure needed to be
modified at times to equalize the treatment cells. These drivers became eligible by