S******9
发帖数: 2837 | 1 40. A study is conducted to investigate the prevalence of past infection
with genital herpes among students attending a large coeducational
Midwestern university. After obtaining informed consent, the study
participants undergo antibody testing for herpes simplex virus 2 (HSV).
Which of the following is the most important factor in determining the
validity of a positive test?
A) The number of sexual partners of the student
B) The proportion of students infected with HSV
C) The proportion of students with negative tests
D) The proportion of students with positive tests
E) The total number of students screened
谢谢 |
z*******2
发帖数: 2643 | 2 Validity of a positive test
= Positive Predictive Value
= Number of true positives/(Number of true positives + Number of false
positives)
= (sensitivity)(prevalence)/[(sensitivity)(prevalence)+(1-specificity)(1-
prevalence)]
Validity of a positive test is positively related to prevalence. prevalence
is The proportion of students infected with HSV.
Therefore, Validity of a positive test is positively related to The
proportion of students infected with HSV.
B. is correct.
【在 S******9 的大作中提到】
: 40. A study is conducted to investigate the prevalence of past infection
: with genital herpes among students attending a large coeducational
: Midwestern university. After obtaining informed consent, the study
: participants undergo antibody testing for herpes simplex virus 2 (HSV).
: Which of the following is the most important factor in determining the
: validity of a positive test?
: A) The number of sexual partners of the student
: B) The proportion of students infected with HSV
: C) The proportion of students with negative tests
: D) The proportion of students with positive tests
|
S******9
发帖数: 2837 | |
S******9
发帖数: 2837 | 4 Validity of a negative test 是不是和specificcity相关？ |
z*******2
发帖数: 2643 | 5 Validity of a negative test 和 specificity 成反比
validity of a negative test
= negative predictive value
= (specificity)(1-prevalence)/[(specificity)(1-prevalence)+(1-sensitivity)(
prevalence)]
=1 - (1-sensitivity)(prevalence)/[(specificity)(1-prevalence)+(1-sensitivity
)(prevalence)]
【在 S******9 的大作中提到】
: Validity of a negative test 是不是和specificcity相关？
|
m*********6
发帖数: 609 | 6 我这些也是老搞混，上个月考step3前又突击了一下，好象当时搞明白了，考试中也有
这方面的题，也不知道答对了没有，现在再一看，概念又模糊了
sensitivity
【在 z*******2 的大作中提到】
: Validity of a negative test 和 specificity 成反比
: validity of a negative test
: = negative predictive value
: = (specificity)(1-prevalence)/[(specificity)(1-prevalence)+(1-sensitivity)(
: prevalence)]
: =1 - (1-sensitivity)(prevalence)/[(specificity)(1-prevalence)+(1-sensitivity
: )(prevalence)]
|
