1. A researcher examines the effects of controlled breaks on reaction times of Air Traffic Controllers. The controllers are randomly assigned to two groups. Group 1 has 20 controllers who spend 45 minutes on a break in a quiet room, with no talking, TV, or other electronics. Group 2 has 20 controllers who spend their 45 minutes on a break in a common area break room where people are allowed to talk, watch TV, or use electronic devices. Following the breaks, each group of controllers returned to their shift where their reaction times were assessed.

1. What type of investigation is this?
2. What are the variables?

1. A researcher wants to determine the effects of a new airfoil coating material on the airfoil's lift and drag abilities. The researcher tests the airfoil in a chamber then applies the coating and tests again measuring the speed that air passes over the airfoil and noting any changes.

1. What type of investigation is this?
2. What are the variables?

1. A research wants to determine the effects of seat choice on an airplane to customer satisfaction. For this research, passengers were allowed to sit wherever they wanted to on two consecutive flights by selecting their seats from among all available.

1. What type of investigation is this?
2. What are the variables?

1. A researcher tested the effect of caffeine on sleep. Forty pilots volunteered to participate in the study and signed up for one of two nights. Pilots on Tuesday night drank a cup of regular coffee, and those on Wednesday night received a cup of decaffeinated coffee. They then took a nap, and the length of time to fall asleep was recorded with the aid of an EEG. Pilots in the caffeine group took significantly longer to fall asleep. The researcher concludes that caffeine interferes with the ability to fall asleep.

1. What type of investigation is this?
2. What are the variables?