Introduction to Epidemiology 6th Edition by Ray M Merrill

Exercise 1

For each of the following statements, indicate whether the statistical association is likely the result of chance, bias, or confounding.

a. A case-control study showed that a strong association exists between birth order and Down syndrome.

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b. A case-control study found a positive association between self-reported chest radiographs during pregnancy and breast cancer.

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c. A randomized clinical trial found that drug A versus placebo did not significantly improve 10-year survival (RR = 0.35; 95% confidence interval, 0.14–55.01).

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d. A cohort study found no statistical association between smoking and pancreatic cancer (RR = 1; P value = 0.85).

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e. A hospital-based case-control study identified a strong association between oral contraceptives and thromboembolism. Many doctors suspected the association and hospitalized some women who used oral contraceptives for evaluation.

Step 1 of 7

Statistical interpretations include providing a conclusion about any features of the population which is relied upon sample data. Through this sample data one can find the result by luck or by chance. The P value and sample size determines the role of chance. The P value ranges from 0 to 1. A small P value displays that the outcome is not the result which comes by chance.

Bias means the outcomes are not similar to the reality and can elucidate all or portion of an experimental suggestion between exposure of the disease and its consequence variables. Bias can only be corrected by proper planning and by doing the research examination.