Biomechanics of novice runners. An article published in Applied Bionics and Biomechanics (Vol. 2021) discusses how the study of the biomechanics of novice runners can help them avoid running injuries if they have understood their own body and determined the safest method to perform an exercise task. This is analogous to the statistical hypothesis-testing process. The null hypothesis is that the novice runner is not injured if he/she has determined the safest method to do a task. The alternative hypothesis is that the novice runner suffers an injury even though he/ she has determined the safest method, which is accepted only when sufficient evidence exists to support it. If the analysis result is in favor of injured, the null hypothesis of not injured is rejected, and the researchers conclude that the novice runner is injured even though he/she has determined the safest method. Researchers never accept the null hypothesis; that is, researchers never declare a result of “not injured” since this would imply that novice runners suffered no injuries after they determined the safest method.

a. Define Type I and Type II errors in this analysis.

b. Which of the two errors is more serious? Explain.

c. The researchers do not, in general, know the values of a and b; but ideally, both should be small. One of these probabilities is assumed to be smaller than the other in a particular sport or exercise task. Which one, and why?

d. The analysis result relies on the belief that the value of a is made very small before injury is concluded. Explain why this is so.

e. For an experiment result against injured, will the value of a increase or decrease? Explain.

f. For an experiment result against injured, will the value of b increase or decrease? Explain.