Biostats

Question 1

Absolute risk reduction

Answer 1

event rate (control) - event rate (tx group)

Question 2

relative risk reduction

Answer 2

absolute risk reduction / event rate (control group)

Question 3

relative risk

Answer 3

event rate (tx group) / event rate (control group)

Question 4

number needed to treat

Answer 4

1 / absolute risk reduction

Question 5

attributable risk (risk difference)

Answer 5

incidence (exposed) - incidence (unexposed)

Question 6

population attributable risk

Answer 6

incidence (total) - incidence (unexposed)

Question 7

population attributable risk percent

Answer 7

(risk in population - risk in unexposed) / risk in population

Question 8

number needed to treat

Answer 8

1 / attributable risk (risk difference)

Question 9

attributable risk percent

Answer 9

attributable risk / incidence (exposed)

Question 10

positive likelihood ratio

Answer 10

sensitivity / (1 - specificity)

Question 11

negative likelihood ratio

Answer 11

(1 - sensitivity) / specificity

Question 12

sensitivity

Answer 12

a / (a+c)

Question 13

specificity

Answer 13

d / (d+b)

Question 14

positive predictive value

Answer 14

a / (a+b)

Question 15

negative predictive value

Answer 15

c / (c+d)

Question 16

When are funnel plots used?

Answer 16

Funnel plots are commonly used in systemic reviews and search for publication bias

Question 17

Selection bias definition

Answer 17

selection of subjects that are not representative of the study population

Question 18

Referral bias definition

Answer 18

occurs when patients are sampled from specialized medical centers and therefore do not represent the general population