Question

9-7. Diagnostic Testing: Baseball Fever

A researcher at Javier Lopez University developed a new test for detecting baseball fever. The new test was evaluated in a population of 10,000 people, 21% of whom were definitely known to have baseball fever. The number of negative tests was 8,162. The positive predictive value was discovered to be 91.4%.

1. Use the information provided above to fill in the following 2 x 2 table:

                                                  Baseball Fever

                                             Present                 Absent

Test Result

    Positive                           ______                 ______

    Negative                         ______              ______

2. What are the test’s sensitivity and specificity? Provide an interpretation of the sensitivity, using the value you just calculated.
3. If you were to apply this test to a patient and the result came back negative, what would you advise that patient regarding his/her chances of having baseball fever?

Answer 1

positive predictive value = number of true positive/total positives

total positive = 10000 - 8162 =1838

number of true positves = positive predictive value*total positives = 91.4% * 1838 = 1680

	fever present	absent	total
positive	1680	158	1838
negatives	420	7742	8162
total	2100	7900	10000

sensitivity = true positve / total fever present = 1680/2100*100=80%

specificity = true negative/total fever absent =7742/7900 = 98%

Sensitivity interpretation-

there is 80% probability of the test correctly identifying baseball fever subjects  

--------------------

If you were to apply this test to a patient and the result came back negative, what would you advise that patient regarding his/her chances of having baseball fever

P(fever present | negative) = 420/8162*100 = 5.15%

so, there is 5.15% chance of having baseball fever after test came neagtive.