「Epi practicals - 12 April 2021」の版間の差分

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!test positive
 
!test positive
 
|316.35
 
|316.35
|26.68
+
|13.37
 
|-
 
|-
 
!test negative
 
!test negative

2021年4月12日 (月) 15:36時点における版

Epi practicals

12 April 2021

Is this test useful

Practical - HIV

  • Q1
With disease Without disease
test positive 152 20
test negative 8 980
  • Q2
    • Sensitivity=[math]\displaystyle{ \frac{152}{160} = 0.95 }[/math]
    • Specificity=[math]\displaystyle{ \frac{980}{1000} = 0.98 }[/math]
  • Q3

a)

With disease Without disease sum
test positive 38 1999.2 2037.2
test negative 2 97960.8 97962.8
sum 40 99,960 100,000
  • Positive predictive value=[math]\displaystyle{ \frac{38}{38+1999.2}=0.0187 }[/math]
  • Negative predictive value=[math]\displaystyle{ \frac{97960.8}{2+97960.8}=0.999 }[/math]

b)

With disease Without disease
test positive 316.35 13.37
test negative 13.34 653.66
sum 333 667
  • Positive predictive value=[math]\displaystyle{ \frac{316.35}{316.35+13.34}=0.959 }[/math]
  • Negative predictive value=[math]\displaystyle{ \frac{653.66}{1999.2+653.66}=0.246 }[/math]
  • Q4

To have high sensitivity is more important, because testing blood donor is a screening test and false-negative has to be excluded as much as possible.

  • Q5

We need to calculate PPV and show the director how much false-positive donors arise.

  • Q6

We should advise the director that donors should be informed to proceed to an additional confirmation test, not just be informed simple positive result.