Biostats

Question 1

Odds ratio used for what studies?

Equations?

Answer 1

Case-control

Ad / bc
OR
a/b) / (c/d

Question 3

Attributable risk = what?

Answer 3

AR = a/(a + b) - c/(c + d)
Or
Basically take the mortality/bad event divided by the total amount in the exposed (Treatment) group and subtract from it the control group bad event

Question 4

Relative risk used in what studies?

Equation?

Answer 4

Cohort

[A/(a+b)] / [c/(c+d)]

Question 6

LR+ = ?

Answer 6

sensitivity / 1 - specificity

Question 7

NNH =?

Answer 7

1/Attributable risk

Attributable risk = ADVERSE event (Death) rate in Treatment group -Adverse event rate in control group

Question 8

Prevalence = ?

Answer 8

existing cases / Total # of people

Question 9

LR- = ?

Answer 9

1 - sensitivity / specificity

Question 10

NNT = ?

Answer 10

1 / ARR

Basically the difference in %’s of a good event due to the experimental treatment

Question 13

Incidence = ?

Answer 13

NEW cases / # at risk

Question 14

Relative risk reduction (RRR) = ?

Answer 14

1 - RR

Ex. If 2% pts who get flu shot get the flu while 8% who do not get the flu, then RR = 2/8 = .25 and RRR = .75