In a study of the relationship for senior citizens between physical activity and

Question

In a study of the relationship for senior citizens between physical activity and frequency of colds, participants were asked to monitor their weekly time spent in exercise over a five-year period and the frequency of colds. The study demonstrated that a negative statistical relation exists between time spent in exercise and frequency of colds. The investigator concluded that increasing the time spent in exercise is an effective strategy for reducing the frequency of colds for senior citizens. a. Were the data obtained in the study observational or experimental data? b. Comment on the validity of the conclusions reached by the investigator. c. Identify two or three other explanatory variables that might affect both the time spent in exercise and the frequency of colds for senior citizens simultaneously. d. How might the study be changed so that a valid conclusion about causal relationship between amount of exercise and frequency of colds can be reached?

Explanation / Answer

A)Observational data because the time for exercises was not set by the investigator.

B)Many other factors may have influenced the study. In particular, there might be common causes for more illness and less exercise, or more illness may reduce the frequency of exercise.

C) Some reasons may have been: financial means, ability, age ,health, etc

D) The conclusions would be more valid if the investigator set up a formal study that included some of the following: individuals who are all in good health, or who are matched in health at the start of the study; controlled amounts of exercise time; recording actual exercise time (e.g. if someone walks to the grocery store, that should be added to the formal exercise time) etc.

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