FACT SHEET

House Concurrent Resolution No. 294, S.D. 1, adopted by the Legislature in the 2005 Regular Session, requested the Bureau to conduct a review of existing studies and statistics on the causal relationship between wireless telephone use while operating a motor vehicle and increased motor vehicle-related accidents.

I. Highlights

1. The studies find that cellular telephone use while operating a motor vehicle is a distraction-inducing action.
2. The studies generally do not prove or disprove that cellular telephone use while operating a motor vehicle is a cause of motor vehicle collisions. Instead, the studies generally find that a statistical association, not necessarily a causal relation, exists between cellular telephone use while operating a motor vehicle and motor vehicle collisions.
3. The studies do not address whether cellular telephone use while operating a motor vehicle is the most prevalent cause of motor vehicle collisions among collisions that are caused by a distraction-inducing action. Instead, the studies address associations, rather than causal relations, between various potential distractions and motor vehicle collisions. However, no definitive answer has yet emerged as to which driver distraction is associated with the greatest risk of crash involvement.
4. Last, the studies find that a hands-free cellular telephone is not much safer than a hand-held cellular telephone. Both tend to be equally distracting. Moreover, the type of phone does not affect the statistical association between phone use and the risk of a crash.

II. Frequently Asked Questions

1. Is causation difficult to prove?
   Answer: Yes. The gold standard for proving causation is the randomized experiment, in which a large number of people are randomly selected and divided into two groups. In this instance, one group would be required to use cellular telephones while driving. The other group would be prohibited from using cellular phones while driving. The task for the experimenters would then be to wait and see which group is involved in more motor vehicle collisions over a period of time.
   Such a study, it is noted, would be very difficult to perform and possibly unethical.
2. How is an association different from causation? Answer: Association means that two or more variables are related in some fashion. In contrast, causation means that two or more variables are causally linked. An association may be circumstantial evidence for causation, it does not prove causation.
   The following are examples of a causal relation between an event A and an event B, in which event A causes event B (taken from the article on "Causality" from Wikipedia, the free encyclopedia, at http://en.wikipedia.org):
   • A cue ball colliding with the eight ball causes the eight ball to roll into the pocket.
   • The presence of heat causes water to boil.
   • The moon's gravity causes the Earth's tides.
   • A good blow to the arm causes a bruise.
   • My pushing of the accelerator causes the car to go faster.
   In contrast, the following are examples of an association between an event A and an event B (taken from the articles on "Causality", "Joint effect", and "Wrong direction", in Wikipedia, the free encyclopedia, at http://en.wikipedia.org, and from Burns, W.C., Spurious Correlations, at http://www.burns.com):
   • Good health was associated with bodily lice infestation, during the Middle Ages. Thus, people of that time incorrectly inferred that the departure of bodily lice caused sickness. The reverse turned out to be the truth. The rise in bodily temperature during a sickness caused the lice to leave.
   • The shoe size of a child is associated with the child's reading skills. Does reading practice cause the feet to grow? Or does growing feet stimulate the desire to read? Neither is correct. With age, a child's reading skills naturally improve and the child's feet naturally grow.