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#1
08-05-2012
 USMLE Forums Master Steps History: 1+CK+CS Posts: 1,866 Threads: 149 Thanked 2,249 Times in 1,096 Posts Reputation: 2269
Calculate the sensitivity from this 2X2 table

An experimental serologic test is developed to detect the presence of HIV antibody. Epidemiological analysis
reveals the results shown below.

People with HIV antibody People without HIV antibody
Positive test 100 50
Negative test 20 950

What is the sensitivity of this test?

A. 11%
B. 67%
C. 83%
D. 95%
E. 98%
 The above post was thanked by: riya rai (08-06-2012)

#2
08-06-2012
 USMLE Forums Master Steps History: 1+CK+CS Posts: 720 Threads: 217 Thanked 569 Times in 317 Posts Reputation: 579

83.

Code for this

SENSITIVE AC.
SPECIFIC BD.
Predicted---- AB,CD(+,-)

All denominators...

Last edited by cingulate.gyrus; 08-06-2012 at 11:14 AM. Reason: correction
#3
08-06-2012
 USMLE Forums Veteran Steps History: 1+CK+CS Posts: 289 Threads: 7 Thanked 149 Times in 116 Posts Reputation: 159

Would be C

#4
08-06-2012
 USMLE Forums Addict Steps History: Not yet Posts: 108 Threads: 15 Thanked 28 Times in 17 Posts Reputation: 38

http://www.usmle-forums.com/usmle-st...tt-square.html
#5
08-06-2012
 USMLE Forums Newbie Steps History: Not yet Posts: 2 Threads: 0 Thanked 3 Times in 1 Post Reputation: 13

C. 83%

Sensitivity = TP / TP + FN = 100 / 100 + 20 = 83.3%

 Tags Biostatistics-Epidemiology, Step-2-Questions

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