17B Preview

Preparing for the next class

In the next in-class activity, you will need to be able to calculate counts for a categorical variable using technology and interpret graphical displays for categorical variables. Recall that 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 in a dataset called “PulseRate.” The variables in the dataset are:

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)

Questions 1–4: Go to the DCMPExplore Categorical Data tool for one categorical variable at https://dcmathpathways.shinyapps.io/EDA_categorical/. Open spreadsheet DCMP_STAT_17A_PulseRate so you can copy and paste the relevant columns into the data analysis tool by selecting “Enter Data: Individual Observations.”

Question 1

1) Using the variable Sex from the dataset, what is the number of males in the sample?

a) 51

b) 59

c) 110

d) 46

Hint: In the tool, choose “Individual Observations,” specify the variable name, and copy and paste the variable values from the spreadsheet into the data analysis tool.

Question 2

2) Delete all of the values for the previous variable. Using the variable Alcohol from the dataset, what is the percentage of students who are regular drinkers? Make sure to specify the variable name in the data analysis tool.

a) 68%

b) 42%

c) 62%

d) 38%

Question 3

3) Using the variable Smokes from the dataset, what is the number of students who do not regularly smoke?

a) 110

b) 11

c) 90

d) 99

Question 4

4) What is the percentage of students who smoke regularly?

a) 11%

b) 99%

c) 90%

d) 10%

Question 5

5) Using the following graphical display, what is the correct interpretation of the boxplot of the first pulse measurement by male/female?

A box plot of first pule by male/female. The x-axis is labeled “Male/Female” and the y-axis is labeled “First Pulse.” For female, the low point is at approximately 60 and the high point is at approximately 105. The low end of the box is at approximately 68, the high end is at approximately 84, and the middle line is at approximately 76. For male, the low point is at approximately 49 and the high point is at approximately 93. The low end of the box is at approximately 66, the high end is at approximately 80, and the middle line is at approximately 75.

a) The median first pulse measurement for males and females is around 75 beats per minute.

b) The mean first pulse measurement for males and females is around 75 beats per minute.

c) The median first pulse measurement for males and females is around 100beats per minute.

d) The mean first pulse measurement for males and females is around 100 beats per minute.

Question 6

6) Using the following graphical display, what is the correct interpretation of the boxplot of the first pulse measurement by exercise frequency?

A box plot of first pule by exercise. The x-axis is labeled “Exercise Frequency” and the y-axis is labeled “First Pulse.” For los, the low point is at approximately 52 and the high point is at approximately 92. The low end of the box is at approximately 70, the high end is at approximately 84, and the middle line is at approximately 78. For moderate, the low point is at approximately 58 and the high point is at approximately 90. The low end of the box is at approximately 68, the high end is at approximately 79, and the middle line is at approximately 76. For high, the low point is at approximately 49 and the high point is at approximately 96. The low end of the box is at approximately 61, the high end is at approximately 76, and the middle line is at approximately 67.

a) The median first pulse measurement is highest for low exercise frequency compared to moderate and high levels.

b) The median first pulse measurement is highest for high exercise frequency compared to low and moderate levels.

c) The median first pulse measurement is highest for moderate exercise frequency compared to low and high levels.

d) The median first pulse measurement is equal for all levels of exercise frequency.