USMLE Forum Archives - USMLE Step 1 - Biostatistics
Biostatistics
drspleen - 03-08-11 21:18
A research group investigates the clinical utility of a new serum marker for prostate cancer. To do this, they analyze serum samples from 700 patients. 380 of these patients had known diagnoses of prostate cancer but had not yet undergone any form of therapy. Their results included:
Cancer patients
Elevated serum marker in 365 patients
Control patients
Elevated serum marker in 128 patients
Given these results, what is the negative predictive value of this serum marker?
drspleen - 03-08-11 21:18
A research group investigates the clinical utility of a new serum marker for prostate cancer. To do this, they analyze serum samples from 700 patients. 380 of these patients had known diagnoses of prostate cancer but had not yet undergone any form of therapy. Their results included:
Cancer patients
Elevated serum marker in 365 patients
Control patients
Elevated serum marker in 128 patients
Given these results, what is the negative predictive value of this serum marker?
The correct answer and explanation will be available after you answer.
Page 1
#2
Re: Biostatistics sudha2015 - 03-09-11 01:08 My answer is: c.
Elevated serum marker in 365 patients
Control patients
Elevated serum marker in 128 patients
Given these results, what is the negative predictive value of this serum marker?
#6
Re: Biostatistics babbu5508 - 03-19-11 19:11 My answer is: a.
Negative predictive value = TN / (FN + TN)....solving roughly by this formula...i get the answer near to 96%....
#7
Re: Biostatistics
drspleen - 03-22-11 15:28 The NPV = d/(c+d) = number of true negative over all patients with negative results. In this case, that would be 192 / 207, or 93%.
Page 1