115 Effect of altitude on climbers. Dr. Philip Lieberman, a neuroscientist at Brown University, conducted a field experiment to gauge the effect of high altitude on a person’s ability to think critically ( New York Times , Aug. 23, 1995).

The subjects of the experiment were five males who took part in an American expedition climbing Mount Everest.

At the base camp, Lieberman read sentences to the climbers while they looked at simple pictures in a book. The length of time (in seconds) it took for each climber to match the picture with a sentence was recorded. Using a radio, Lieberman repeated the task when the climbers reached a camp 5 miles above sea level. At this altitude, he noted that the climbers took 50% longer to complete the task.

a. What is the variable measured in this experiment?

b. What are the experimental units?

c. Discuss how the data should be analyzed.