NBME CBSE STEP 1 EXAM UPDATED
PRACTICE SOLUTION BUNDLED REVIEW
SHEET TESTED ANSWERS
⩥ How does negative predictive value vary?
Answer: Inversely with prevalence or pretest probability
⩥ What does the receiver operating characteristic (ROC) curve
demonstrate?
Answer: How well a diagnostic test can distinguish between two groups
⩥ What does the ROC curve plot?
Answer: True positive rate (sensitivity) against false positive rate (1-
specificity)
⩥ What does a better performing test have in terms of the ROC curve?
Answer: Higher area under the curve (AUC) and closer to the upper left
corner
⩥ What is precision?
Answer: Consistency and reproducibility of a test
, ⩥ What decreases precision?
Answer: Random variation or random error
⩥ What happens when precision increases?
Answer: Lower standard deviation (SD) and higher statistical power
(beta)
⩥ What is accuracy?
Answer: Closeness of test results to true values
⩥ What decreases accuracy?
Answer: Systematic error or bias in a test
⩥ What is incidence?
Answer: Number of new cases divided by the number of people at risk
⩥ What is prevalence?
Answer: Number of existing cases divided by the number of people in
the population
⩥ What is the formula for calculating prevalence?
Answer: Prevalence = incidence rate * average duration of disease / (1 -
prevalence)
PRACTICE SOLUTION BUNDLED REVIEW
SHEET TESTED ANSWERS
⩥ How does negative predictive value vary?
Answer: Inversely with prevalence or pretest probability
⩥ What does the receiver operating characteristic (ROC) curve
demonstrate?
Answer: How well a diagnostic test can distinguish between two groups
⩥ What does the ROC curve plot?
Answer: True positive rate (sensitivity) against false positive rate (1-
specificity)
⩥ What does a better performing test have in terms of the ROC curve?
Answer: Higher area under the curve (AUC) and closer to the upper left
corner
⩥ What is precision?
Answer: Consistency and reproducibility of a test
, ⩥ What decreases precision?
Answer: Random variation or random error
⩥ What happens when precision increases?
Answer: Lower standard deviation (SD) and higher statistical power
(beta)
⩥ What is accuracy?
Answer: Closeness of test results to true values
⩥ What decreases accuracy?
Answer: Systematic error or bias in a test
⩥ What is incidence?
Answer: Number of new cases divided by the number of people at risk
⩥ What is prevalence?
Answer: Number of existing cases divided by the number of people in
the population
⩥ What is the formula for calculating prevalence?
Answer: Prevalence = incidence rate * average duration of disease / (1 -
prevalence)
