The paper "The Impact of Information Disclosure on Consumer Behavior" described a study of the ordering behavior of
diners at full-service restaurants on a college campus. When parties of diners checked in to be seated, some parties
received the usual set of menus, and some parties received identical menus with the addition of calorie labels. The
researchers were interested in whether receiving information about the number of calories in each menu item would
influence what the diners ordered. The researchers summarized their conclusions with the following statement: "We
estimate that the labels resulted in a 3.0% reduction in calories ordered, with the reduction occurring in appetizers and entrees but not drinks or desserts." Indicate whether the study is an observational study or an experiment. Give a brief explanation for your choice.

This is an observational study because the researchers recorded what each diner ordered.
This is an experiment because the parties of diners were randomly selected to have a meal at a full-service
restaurant on a college campus.
This is an experiment because the diners were assigned different experimental conditions (the usual menus
or menus with calorie labels.)
This is an observational study because the participants responded to a survey of what menu items they
ordered at the restaurants.