Interaction Terms – Learn It 1

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Interaction Terms – Learn It 1

Know what an interaction term is and use a scatterplot to understand the interaction effects
Write appropriate multiple linear regression model equations for categorical predictors and interaction terms

Students in an introductory statistics class at The University of Queensland participated in a simple experiment.^[1] The students took their own pulse rates. They were then asked to flip a coin. If the coin came up heads, they were to run in place for one minute. Otherwise, they sat for one minute. Afterward, everyone took their pulse rates again. The pulse rates and other physiological and lifestyle data were recorded. There are a total of [latex]110[/latex] observations and [latex]11[/latex] variables.

Research Question: How does Pulse1 depend on the weight of the student and their frequency of exercise?

Wilson, R. J. (n.d.). Pulse rates before and after exercise. StatSci.org. http://www.statsci.org/data/oz/ms212.html ↵

Variable	Description
ID	Identification number
Height	Height in centimeters (cm)
Weight	Weight in kilograms (kg)
Age	Age in years
Sex	Male/female
Smokes	Are you a regular smoker? (yes/no)
Alcohol	Are you a regular drinker? (yes/no)
Exercise	What is your frequency of exercise? (low, moderate, high)
GroupAssignment	Whether the student ran or sat between the first and second pulse measurements
Pulse1	First pulse measurement (rate per minute)
Pulse2	Second pulse measurement (rate per minute)
Year	Year of class (1993–1998)