Exposure to low-frequency sound. Infrasound refers to sound frequencies below the audibility range of the human ear. A study of the physiological effects of infrasound was published in the Journal of Low Frequency Noise, Vibration and Active Control (Mar.

2004). In the experiment, one group of five university students (Group A) was exposed to infrasound at 4 hertz and 120 decibels for 1 hour, and a second group of five students (Group B) was exposed to infrasound at 2 hertz and 110 decibels, also for 1 hour. The heart rate (beats/minute) of each student was measured both before and after exposure. The experimental data are provided in the accompanying table. To determine the impact of infrasound, the researchers compared the mean heart rate before exposure to the mean heart rate after exposure.

a. Analyze the data on Group A students with an ANOVA for a randomized block design. Conduct the ANOVA test of interest with a = .05.

b. Repeat part a for Group B students.

c. Now analyze the data via a paired difference t-test.
Show that, for both groups of students, the results are equivalent to the randomized block ANOVA.

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Group A Before After Group B Before After Students Exposure Exposure Students Exposure Exposure A1 A2 A3 A4 A5 PORFI 70 70 B1 69 80 B2 76 84 B3 77 86 B4 64 76 B5 26525 73 79 68 61 69 72 77 61 24886 60 66