A researcher wished to compare the effect of the frequency of the rate of stepping on heart rate in a step-aerobics workout. A collection of 30 adult volunteers, 15 women and 15 men, was selected from a local gym. The men were randomly divided into three groups of five subjects each. Each group did a standard step-aerobics workout, with group 1 at a low rate of stepping, group 2 at a medium rate of stepping, and group 3 at a rapid rate. The women were also randomly divided into three groups of five subjects each. As with the men, each group did one of the three standard step-aerobics workouts. The mean heart rate at the end of the workout for all subjects was determined (in beats per minute). A partial ANOVA table for these data is given below. Analysis of variance for heart rate: The plots and the P-value for the test for interaction show little evidence of interaction, which means that:
A)there is little difference in the heart rates of men and women.
B)the change in heart rate due to the different stepping rates is similar for men and women.
C)changes in stepping rate are positively associated with heart rate.
D)step exercise is equally beneficial to men and women.

Question

A researcher wished to compare the effect of the frequency of the rate of stepping on heart rate in a step-aerobics workout. A collection of 30 adult volunteers, 15 women and 15 men, was selected from a local gym. The men were randomly divided into three groups of five subjects each. Each group did a standard step-aerobics workout, with group 1 at a low rate of stepping, group 2 at a medium rate of stepping, and group 3 at a rapid rate. The women were also randomly divided into three groups of five subjects each. As with the men, each group did one of the three standard step-aerobics workouts. The mean heart rate at the end of the workout for all subjects was determined (in beats per minute). A partial ANOVA table for these data is given below. Analysis of variance for heart rate:  The plots and the P-value for the test for interaction show little evidence of interaction, which means that:
A)there is little difference in the heart rates of men and women. 
B)the change in heart rate due to the different stepping rates is similar for men and women. 
C)changes in stepping rate are positively associated with heart rate. 
D)step exercise is equally beneficial to men and women.

Quizplus · Accepted Answer

Little evidence of interaction means that the effect of the different stepping rates on heart rate is similar for men and women. It does not give any information on the heart rate difference between men and women or the association between stepping rate and heart rate. Therefore, the correct answer is B.

A Researcher Wished to Compare the Effect of the Frequency