An article in Science magazine (Service, 1994) discussed a study comparing the h

Question

An article in Science magazine (Service, 1994) discussed a study comparing the health of 6000 vegetarians and a similar number of their friends and relatives who were not vegetarians. The vegetarians had a 28% lower death rate from heart attacks and a 39% lower death rate from cancer, even after the researchers accounted for differences in smoking, weight, and social class. In other words, the reported percentages were the differences remaining after adjusting for differences in death rates due to those factors. Is the study an observational study or an experiment? Experiment because researchers accounted for smoking, weight, and social class. Observational study because the two groups being compared (vegetarians and non-vegetarians) were chosen by the observational unit rather than by the researcher. Observational study because heart attacks and death from cancer was observed not assigned. Observational study because researchers accounted for smoking, weight, and social class. On the basis of this information, can we conclude that a vegetarian diet causes lower death rates from heart attacks and cancer? Yes, because the difference in death rates was so high between the two diets. Yes, because researchers accounted for smoking, weight, and social class in their analysis. No, because diet was not randomly assigned. No, because it does not say this is a random sample of vegetarians and non-vegetarians.

Explanation / Answer

question 9

(b) because the two groups being compared were chosen by the the observational unit rather than by the researcher.

question 10

It is because of the existence of a virtually unlimited number of potential lurking variables that we can never be 100% certain of a claim of causation based on an observational study.

The key to establishing causation is to rule out the possibility of any lurking variable, or in other words, to ensure that individuals differ only with respect to the values of the explanatory variable.

As most of the common lurking variables are adjusted for i think we go for

(b) yes, because the researchers accounted for smoking,weight and social class in their analysis.

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.