Estimating Risk practice question and answer

Practice Question 1
1.1 If the six month disease risk is=0 the six month disease odds= 0
1.2 If the six month disease odds=2 then the six month risk of disease = 0.67
𝑜𝑑𝑑𝑠
𝑃 = ( 1+𝑜𝑑𝑑𝑠 )
1.3 As disease risk approaches 100% then the disease odds. Become infinite in value
disease odds

1.4 For rare disease the odds of disease is approximately equal to the risk fo disease



Practice Question 2: Relative Risk(RR) vs. Risk Difference (RD)
2.1 A value of the RR=1 implies that RD= 0
2.2 A value of the RR<1 implies that RD= less than 0
2.3 A value of the RR>1 implies that RD= Greater than 0
Risk difference is alos known as attributable risk for the exposed !!


Practice Question 3: Minimum and Maximum Values: RR Vs. RD
3.1 Minimum value for RR= 0
- Because RR should be between 0~ ∞
3.2 What, if anything, can we say about the RD when the RR takes on its minimum
value?
- Let p1 denote disease risk for exposed subjects while p0 denotes disease risk for
𝑝1
unexposed subjects. Thus 𝑅𝑅 = 𝑝0
= 0 implies only that the
𝑅𝐷 = 𝑝1 − 𝑝0 =− 𝑝0 < 0
3.3 The maximum value for the RD = +1
3.4 What if anything can we say about RR when the RD takes on its minimum
value?
- The minimum value of the 𝑅𝐷 = 𝑝1 − 𝑝0 = 0 − 1 =− 1 which implies that the RR=0