Chapter·BiostatisticsP-values and confidence intervals

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1

Group of 100 medical students took an end of the year exam. The mean score on the exam was 70%, with a standard deviation of 25%. The professor states that a student's score must be within the 95% confidence interval of the mean to pass the exam. Which of the following is the minimum score a student can have to pass the exam?

A45%

B63.75%

C67.5%

D20%

E65%

2

You are conducting a study comparing the efficacy of two different statin medications. Two groups are placed on different statin medications, statin A and statin B. Baseline LDL levels are drawn for each group and are subsequently measured every 3 months for 1 year. Average baseline LDL levels for each group were identical. The group receiving statin A exhibited an 11 mg/dL greater reduction in LDL in comparison to the statin B group. Your statistical analysis reports a p-value of 0.052. Which of the following best describes the meaning of this p-value?

AThere is a 95% chance that the difference in reduction of LDL observed reflects a real difference between the two groups

BThough A is more effective than B, there is a 5% chance the difference in reduction of LDL between the two groups is due to chance

CIf 100 permutations of this experiment were conducted, 5 of them would show similar results to those described above

DThis is a statistically significant result

EThere is a 5.2% chance of observing a difference in reduction of LDL of 11 mg/dL or greater even if the two medications have identical effects

3

A randomized control double-blind study is conducted on the efficacy of 2 sulfonylureas. The study concluded that medication 1 was more efficacious in lowering fasting blood glucose than medication 2 (p ≤ 0.05; 95% CI: 14 [10-21]). Which of the following is true regarding a 95% confidence interval (CI)?

AIf the same study were repeated multiple times, approximately 95% of the calculated confidence intervals would contain the true population parameter.

BThe 95% confidence interval is the probability chosen by the researcher to be the threshold of statistical significance.

CWhen a 95% CI for the estimated difference between groups contains the value ‘0’, the results are significant.

DIt represents the probability that chance would not produce the difference shown, 95% of the time.

EThe study is adequately powered at the 95% confidence interval.

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