This report presents the results of a study conducted for the National Highway Traffic Safety Administration (NHTSA) to assess the effects of two programs that were implemented to reduce the incidence of aggressive driving. The programs were conducted by the Marion County Traffic Safety Partnership (Indianapolis, Indiana), and The Tucson, Arizona, Police Department.
Samples of vehicle speed, collected unobtrusively in the special enforcement zones, and crash incidence served as the primary measures of the programs' effect. The total number of crashes in the Marion County special enforcement zones increased by 32 percent, compared to the same six-month period one year earlier; the number of those crashes with primary collision factors (PCFs) associated with aggressive driving increased by 41 percent. That is, the total number of crashes increased, but the crashes with aggressive driving PCFs increased at a greater rate. The change in proportion of crashes with the target PCFs provides a better measure than crash frequency because it eliminates the effects of changes in traffic volume and other factors that might have contributed to the overall increase in crash incidence.
In this regard, the Marion County zones experienced a six percent increase in the proportion of all crashes with aggressive driving PCFs, despite the extensive publicity and special enforcement efforts. The number of crashes in Tucson’s special enforcement zones increased by ten percent, but the number of crashes with aggressive driving PCFs increased by less than one percent. More important, the proportion of all crashes with target PCFs decreased by eight percent. That is, crash incidence increased overall in Tucson’s zones, but the proportion of those crashes with aggressive driving PCFs declined.
The original purpose of this report was to present, rather than compare, the two aggressive driving programs. However, comparisons are inevitable and the substantially different results of the two programs require an explanation. First, it is important to understand that it is impossible to control all of the variables that could influence the outcome of a study when conducting large-scale quasi-experiments, such as the programs described in this report. Highway maintenance projects and large residential developments that increase traffic volumes on surface streets are examples of unexpected and uncontrolled variables that can affect dependent measures in a field study involving driver behavior. Every attempt was made to identify and control relevant variables within each program, but the research was not originally designed to support systematic comparisons between the two programs. Marion County, Indiana, and Tucson, Arizona, are different in many ways, and it is possible that some of those differences could be responsible for the differential results reported here.
1. What is the main idea of this passage?
(A) The causes and effects of road rage
(B) A study on two aggressive driving programs
(C) A comparison of Marion County, Indiana to Tucson, Arizona
(D) A new proposal for highway maintenance
(E) The recent increase in fatal traffic accidents
Answer choice B is correct because it summarizes the overall argument and takes into account the entire passage, without adding any outside information. Answer choices A, D, and E are all out of scope. Answer choice C is too narrow (the last paragraph states that the comparison is inevitable, but this not the main idea of the passage).
2. What is the primary purpose of this passage?
(A) To mediate between two traffic research syndicates
(B) To identify which factors have the most influence on PCFs
(C) To present a theory explaining how location affects collision frequency
(D) To defend the validity of a study on two aggressive driving programs
(E) To compare and discuss the results of a study of aggressive driving programs
Answer choice E is correct because the author's purpose is to "discuss" and, because it becomes inevitable, to "compare" the two studies of aggressive driving. The author does not "mediate between" the studies, "identify which factors" influence PCFs, "present a theory," or "defend the validity" of the studies.
3. Which of the following is an accurate summary of the passage?
(A) This passage examines the science of human behavior using the example of a study performed in Marion County, Indiana about traffic accidents. It suggests that certain human behaviors can have adverse effects on traffic conditions and even cause major traffic accidents. The results of the study are discussed, and suggestions for reducing aggression are presented.
(B) This passage explores the relationship between location and aggressive driving. The drivers who participated in a study in Indiana were more likely to get into traffic accidents because of certain features of the area, such as residential developments and increased traffic volume. The passage then introduces the finding that aggressive driving does not cause nearly as many traffic accidents in Tucson, Arizona.
(C) The passage presents the results of two studies on aggressive driving behavior. Although each study observed that the number of auto crashes increased, the proportion of crashes caused by aggressive driving rose in one study and declined in the other. Inherent differences in the locations of the two studies are discussed, and the author suggests that these differences affect the studies' results.
(D) The passage attempts to defend the unpopular theory that aggressive driving is the leading cause of accidents in America. Evidence linking aggressive driving to fatal car accidents is given, and two strategies are proposed to counteract the effects of aggression: providing counseling for drivers and creating "special enforcement zones" where police can stop aggressive drivers.
(E) The passage theorizes that PCFs (Primary Collision Factors) have a major effect on traffic accidents, increasing their number by a large percentage each year in some places. One supporting example of this phenomenon is then explored: the results of a study that links a variety of variables, including location, traffic volume, and the creation of "special enforcement zones," to an increase in the number of traffic accidents.
Answer choice C is correct because it accurately summarizes the information presented in each paragraph of the passage. The first paragraph states that the passage will present the results of two studies. The second paragraph presents the results of the Marion County study. The third paragraph compares the results of the Marion County study to the results of the Tucson study, focusing on the differences. The fourth paragraph suggests that the different results are due to the different locations of the two studies. Answer choice C combines each of these summaries into an accurate summary of the entire passage.
4. What attitude is expressed by the author of this passage?
(A) Mournfulness for the victims of traffic accidents
(B) Objective commitment to scientific accuracy
(C) Bewilderment at unexpected results
(D) Enthusiasm for increased law enforcement
(E) Disappointment in aggressive drivers
Answer choice B is correct because the author's attitude is neutral, scientific, and objective, not mournful, bewildered, enthusiastic, or disappointed. The language of the passage supports the neutral attitude of the author, as evidenced by language like: "presents the results of a study," "the substantially different results of the two programs require an explanation," "it is important to understand that it is impossible to control all of the variables," and "every attempt was made to identify and control relevant variables."
5. The phrase might have contributed at the end of the second paragraph contributes to the tone of the passage in which of the following ways?
(A) It reinforces the timid, uncertain tone the author takes toward the research.
(B) It exemplifies the carefully analytical tone the author takes.
(C) It evokes the sarcastic tone present throughout the second paragraph.
(D) It marks a shift from certainty to uncertainty in the author's tone.
(E) It helps create suspense and foreboding in the passage.
Answer choice B is correct because the author is writing in a scientific and objective tone. The author's tone is not "sarcastic" or "uncertain," but rather "carefully analytic," since the author is taking into account possible causes of crashes. The tone certainly does not create "suspense and foreboding," as it is an analytic passage.