What would happen to the predictive value positive if this test were administered in a population with a disease prevalence of 1% instead o

Question 17

What would happen to the predictive value positive if this test were administered in a population with a disease prevalence of 1% instead of 30%? (Note that the sensitivity and specificity of the test remain the same.)

Answer

Predictive value positive would remain the same.

Predictive value positive would increase.

Predictive value positive would decrease.

Question 18

The following information applies to questions 18 through 20.

The association between cellular telephone use and the risk of brain cancer was investigated in a case-control study. The study included 475 cases and 400 controls and the following results were seen:

Cases

Controls

Cellular Phone User

Yes

270

200

470

No

205

200

405

Total

475

400

475

Calculate the odds ratio based on these data.

Answer

OR = (200*205) / (270*200) = 0.76

OR = (270/475) / (200/400) = 1.33

OR = (270/470) / (200/405) = 1.80

OR = (270*200) / (200*205) = 1.32

 

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