A behavioral analysis of incentive prompts for motivating seat belt use

The seat belt usage of drivers was observed at the entrance to two campus parking lots during morning arrival times. After 11 days of baseline, fliers which prompted seat belt wearing were handed to drivers of incoming vehicles. At one parking lot all fliers offered a chance to win a prize (noncontingent rewards); while at the second lot only those fliers given to seat belt wearers included a chance to win a prize (contingent rewards). After 24 consecutive observation days, these interventions were removed for 14 days of withdrawal. The recording of vehicle license plates enabled an analysis of belt usage per individual over repeated exposures to the experimental conditions. At the lot with the contingent reward intervention, mean belt usage was 26.3% during baseline, 45.7% during treatment, and 37.9% during withdrawal. At the noncontingent reward lot, the mean percentage of belt wearing was 22.2% during baseline, 24.1% during treatment, and 21.8% during withdrawal. The analysis of repeated exposures per individual verified that only contingent rewards influenced substantial increases in belt wearing, and showed that most of the influence occurred after the initial incentive prompt.     

A note on the use of mood's likelihood ratio test for item analyses involving 2 × 2 tables with small samples

Mood's likelihood ratio test is generally considered an unreliablex ² approximation in 2 × 2 contingency tables containing expected cell frequencies less than five. Probability values were computed for 60 such tables as part of an item analysis for two 30-item alternate forms of a measure. The rank orders of the items, from best to worst differentiators, as determined separately by Mood's test and by Fisher's exact test correlated .97 for one form and .96 for the other.     

A coefficient of imbalance for content analysis

This article presents a Coefficient of Imbalance applicable to any type of communication that may be classified into favorable content, unfavorable content, neutral content, and non-relevant content. The combined influence of the average presentation of relevant content and the average presentation of total content is reduced to two components, the coefficients of favorable imbalance and of unfavorable imbalance. A precise definition of imbalance is developed and measured against ten criteria.The authors wish to express their appreciation to Mr. Harold Elsten, Dr. Natan C. Leites, and Mr. Ithiel Pool for valuable suggestions and criticisms.     

"Flash for life": Community-based prompting for safety belt promotion

A community-based strategy for promoting safety belt use was field-tested in two adjacent rural communities, one populated by a preponderance of students, faculty, and staff of a major university. The intervention involved the front-seat passenger of a stopped vehicle displaying to the driver of an adjacent, stopped vehicle an 11 x 14 inch flash card that read, "PLEASE BUCKLE UP-I CARE." If the driver buckled up, the "flasher" flipped over the card and displayed the message, "THANK YOU." This flash card was shown to 1,087 unbuckled drivers; 82% of these drivers looked at the flash card and 22% of these complied with the buckle-up request. Compliance was not influenced by the age or gender of the "flasher" (young child vs. college student), nor by the gender of the driver; but significantly more drivers in the university town buckled up following the flash card presentation (25% mean compliance in the college town vs. 14% in the other community). To date, over 2,000 individuals have received a buckle-up flash card for their own use.