Phones and driving: Almost all states in the United States prohibit texting while driving, and several states prohibit all phone use while driving. To determine the extent to which using a phone increases the risk of a traffic accident, a researcher examines accident reports to obtain data about the number of accidents in which a driver was using a phone.

a. Is this a randomized experiment or an observational study?

b. Assume that the accident reports show that people were more likely to have an accident while using a phone. Could this result be due to confounding? Explain.