10 free USMLE Step 1 practice questions in the real exam format, covering the official content areas, with an explanation for every answer.
USMLE Step 1 Practice Test 8Tutor mode
Question 1 of 10
Biostatistics & Epidemiology/Population Health
Investigators measure a serum marker in a large group of people with a disease and a large group of people without it. The figure shows the distribution of values in each group; higher values indicate disease. The investigators want to use the marker as a confirmatory test after a positive screening test, so the cutoff must produce no false-positive results while identifying as many people with the disease as possible. Values at or above the cutoff are called positive. Which of the following cutoff points best meets these requirements?
Distribution of marker values in people with and without the disease
Vertical dashed lines A–E are possible cutoff values. Each curve shows the number of people at each marker value. Figure not drawn to scale.