Elle wanted to test how temperature affects the rate of evaporation. She had three setups:

Setup 1: Elle placed a container with 1 cup of water at room temperature
(25°C).

Setup 2: Elle placed a container with 1 cup of water in a warm room (45°C).

Setup 3: Elle placed a container with 1 cup of water in a cold room (0°c).

Which setup was the control?

In an experiment examining the effects tai chi on arthritis pain, callahan (2010) selected a large sample of individuals with doctor-diagnosed arthritis. half of the participants immediately began a tai chi course and the other half (the control group) waited 8 weeks before beginning. at the end of 8 weeks, the individuals who had experienced tai chi had less arthritis pain that those who had not participated in the course.