The Hawthorne Works was a large Western Electric factory with 45,000 employees. During the 1920s and 1930s Hawthorne Works was the site of some well-known industrial studies. In one of the studies, researchers investigated the impact of different working conditions on worker productivity. Prior to the start of the study, researchers secretly measured workers' productivity for several weeks. Then researchers chose two workers, who then chose their own teams. The teams were separated from the general workforce and completed their work in different experiment rooms where the researchers could observe them more easily. Over a 5-year period researchers manipulated the structure of the workday for each team (number and duration of breaks and number of hours per shift). For each of these changes in working conditions, the researchers measured the effect on productivity. For some conditions, such as frequent short breaks, workers rebelled by intentionally decreasing productivity.

Which of the following features is used in the design of this experiment?Check all that apply.

Group of answer choices

Single blinding

Random assignment

Control group

Direct control of confounding variables

Treatment group