Researchers from the University of California, Berkeley wondered whether upper-class individuals behave more unethically than lower-class individuals. To further investigate this question, researchers studied behaviors of drivers in different makes and models of cars at an intersection in the San Francisco Bay Area on three weekdays between 2:00 p.m. and 5:00 p.m. in June 2011. Cars were rated on a scale from 1 to 5 based on make, age, and physical appearance of the car. For each of the 152 cars, a researcher recorded whether the car yielded to a pedestrian placed in a crosswalk as is required by the California Vehicle Code. Is this study an observational study or a randomized experiment