Question

Coffee stations in offices often just ask users to leave money in a tray to pay for their​ coffee, but many people cheat. On some​ days, researchers at Newcastle University replaced the picture of flowers on the wall behind the coffee station with a picture of staring eyes. They found that the average contribution increased significantly above the​ well-established standard when people felt they were being​ watched, even though the eyes were patently not real. Complete parts a through c below.

​a) Was this a​ survey, an observational​ study, or an​ experiment?

This was ▼ an observational study a survey an experiment because the researchers ▼ did not control the situation; they only observed it. had people answer questions. controlled the situation by determining which picture was used.

​b) Identify the variables.

The treatment is the ▼ average contribution from the participants. picture that is displayed behind the coffee station. number of participants in the study. T

he response was the ▼ number of participants in the study. picture that is displayed behind the coffee station. average contribution from the participants. ​

c) What does​ "increased significantly" mean in a statistical​ sense?

A. The amount collected increased by at least​ 50%.

B. Not enough was collected until the picture with the staring eyes was used.

C. The differences in money collected were larger than could be reasonably attributed to usual​ day-to-day variation.

D. The amount collected increased by at least​ 5%.

Answer 1

​a) Was this a​ survey, an observational​ study, or an​ experiment?

This was an experiment because the researchers controlled the situation by determining which picture was used.

​b) Identify the variables.

The treatment is the picture that is displayed behind the coffee station.

The response was the average contribution from the participants. ​

c) What does​ "increased significantly" mean in a statistical​ sense?

C. The differences in money collected were larger than could be reasonably attributed to usual​ day-to-day variation.