Application of Behavior Change Theory to the Development

BEHAVIOR CHANGE THEORY
the standard letter when combined with variables that demonstrated independent
effects.
These authors recommended further research into the content dimensions and types of
both warning and reinforcement letter treatments.
Kaestner and Speight (1975)
RATINGS:
Design Quality: 12/24
Last Chance Warning Letter: 10/33
The Oregon Traffic Safety Commission and the Motor Vehicles Division of the Oregon
Department of Transportation conducted this study jointly. At the time of this research
(1975), the authors reported that relatively little was known about the value of negligent
operator programs and their component parts.
The objective of this study was to compare the results of a driver improvement
suspension with those of the other four treatments: no contact, a last-chance warning
letter, a probationary license, and a defensive driving course. However, only the
efficacy of the warning letter is considered in this paper.
The 960 drivers selected for this study were drawn from a set of negligent operators
eligible for suspension of their driving privileges and randomly assigned to the five
treatments. Then, subsequent one-year driving records were compared between the
four conditions and the standard suspension. Although there was a no-action control
group, the authors were not primarily interested in the warning letter/control group
comparison.
The study did not provide sufficient information to determine whether or not the
various groups demonstrated similar subject characteristics. In addition, since
“significant departures” from the research plan occurred because the defensive driving
courses were only available in Portland, Salem, and Eugene, there are concerns that the
researchers were not blinded to the randomization schedule. Finally, the authors
selected an alpha level of 0.20 (Marsh, 1971) but since the comparisons of interest are all
directional, the tabled 0.20 χ 2 values are actually one-tailed 0.10 values (Klugh, 1974).
No significant differences were identified between the suspension and the last-chance
warning letter groups for success percentages or average delay in days to failure
(moving violation or chargeable collision) for drivers in cities, rural areas, or combined.
While the authors viewed these findings as failures of the warning letter, it also could
be argued that a simple warning letter has the same deterrent effect as Oregon’s
program of discretionary suspension.
Regarding conformity with the TTM (Table 10), the last chance warning letter
(Appendix B-15) utilized two of the six general strategies (systematic feedback and
express empathy), two of five early stage methods (consciousness raising and dramatic
relief), and none of the late stage techniques.
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