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#1
08-05-2012
 USMLE Forums Master Steps History: 1+CK+CS Posts: 1,867 Threads: 149 Thanked 2,106 Times in 1,049 Posts Reputation: 2126
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 552 Times in 309 Posts Reputation: 562

83.

Code for this

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

All denominators...

Last edited by cingulate.gyrus; 08-06-2012 at 10:14 AM. Reason: correction
#3
08-06-2012
 USMLE Forums Veteran Steps History: 1+CK+CS Posts: 289 Threads: 7 Thanked 129 Times in 102 Posts Reputation: 139

Would be C

#4
08-06-2012
 USMLE Forums Addict Steps History: Not yet Posts: 108 Threads: 15 Thanked 23 Times in 14 Posts Reputation: 33

answer is: (C). 83%

2X2 Statistics / Epidemiology Table (Punnett Square)
#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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