Two cross-sectional studies were conducted using different questionnaires to determine the prevalence of over-the-counter analgesics use in a population. The first study showed a prevalence of 7.5% (95% confidence interval 6.0 - 9.0), and the second study demonstrated a prevalence of 7.3% (95% confidence interval 6.9 - 7.6). If the true prevalence of over-the-counter analgesics use in the population is 7.4%, which of the following statements about the results of the study is the most accurate?

Question

Two cross-sectional studies were conducted using different questionnaires to determine the prevalence of over-the-counter analgesics use in a population.  The first study showed a prevalence of 7.5% (95% confidence interval 6.0 - 9.0), and the second study demonstrated a prevalence of 7.3% (95% confidence interval 6.9 - 7.6).  If the true prevalence of over-the-counter analgesics use in the population is 7.4%, which of the following statements about the results of the study is the most accurate?

Quizplus · Accepted Answer

Precision is the measure of random error in the study. The study is precise if the results are not scattered widely; this is reflected by a tight confidence interval. The first study has a wider confidence interval compared to the second study; therefore, the second study is more precise. (Choices A and B) Specificity and sensitivity are measures of validity. The sensitivity and specificity of the questionnaires used in these studies cannot be determined from the given information. (Choices C and D) Validity and accuracy are measures of systematic error (bias). Accuracy is reduced if the result does not reflect the true value of the parameter measured. Increasing the sample size increases the precision of the study, but does not affect accuracy. In our case, the results of both studies are pretty close to the true value, and are thus seemingly accurate. Educational Objective: Precision is the measure of random error. The tighter the confidence interval, the more precise the result. Increasing the sample size increases precision.

Two Cross-Sectional Studies Were Conducted Using Different Questionnaires to Determine