Question 14.44

14.44 Public transit use and physical activity.

In one study on physical activity, participants used accelerometers and a seven-day travel log to monitor their physical activity.7 Researchers used the data from each participant to quantify the amount of daily walking and to classify each as a non-transit user, or a low-, mid-, or high-frequency transit user. Below is a summary of physical activity (in minutes per day) broken down into walking and non-walking activities.

  1. Would this be considered an observational study or an experiment? Explain your answer.
  2. What are the numerator and denominator degrees of freedom for the tests?
  3. State the null and alternative hypotheses associated with each of the overall -values.
    Physical activity Nontransit
    		 Low frequency
    		 Mid frequency
    		 High frequency
    		 Overall
    -value
    Walking 21.8a 25.8a,b 34.4b,c 36.5c <0.001
    Nonwalking 16.0 13.5 11.9 15.2 0.24
  4. The superscript letters in each row summarize the multiple comparisons results. Write a short paragraph explaining what these results tell you with regard to walking and non-walking physical activity.

751