Measures of Association

Question 1

Absolute difference

Answer 1

subtraction

group 1 = 135
group 2 = 25

group 1 had 110 more outcome occurrences
group 2 had 110 less outcome occurrences

Question 2

Relative frequency

Answer 2

group 1 = 135
group 2 = 25

25/135

G 2 had less thn 20 % of the outcomes seen in group 1
G 1 had over 5 times the number of cases

Question 3

Risk Ratio: probability of outcome in exposed, Risk in exposed

Answer 3

A / (A+B)

Question 4

Risk Ratio: probability of outcome in non-exposed, Risk in non-exposed

Answer 4

C/(C+D)

Question 5

Incidence Risk (IR)

Answer 5

Risk Ratio

Risk in exposed
Risk in non-exposed

Question 6

Absolute Risk Reduction

Answer 6

IR G1 - IR G2
if risk is 1.5 in exposed and 1.2 in nonexposed,

1.5-1.2 = answer

Question 7

Relative Risk Reduction

Answer 7

Absolute Risk Reduction/R in unexposed

Question 8

NNT & NNH

Answer 8

number needed to treat & number needed to harm

1/Absolute Risk Reduction

always round to whole number before interpreting

3.6 = NTH = 4 people out of every 100 were harmed.

Question 9

Odds of exposure in cases

Answer 9

A/C

Question 10

Odds of exposure in controls

Answer 10

B/D

Question 11

Odds ratio

Answer 11

(A/C) / (B/D)

Question 12

crude morbidity rate

Answer 12

of persons with disease / # in population

Question 13

crude mortality rate

Answer 13

of deaths / # in population

Question 14

Cause specific mortality rate

Answer 14

of cause specific deaths / # in population

Question 15

Case-fatality rate

Answer 15

of cause specific deaths / # of cases of disease

Question 16

Cause-specific survival rate

Answer 16

of cause-specific cases alive /# of cases of disease

Question 17

Live birth rate

Answer 17

of births / 1000

Question 18

Fertility rate

Answer 18

of live births / 1000 women of childbearing age

Question 19

Proportional mortality ratio

Answer 19

of causes specific deaths/ total # of deaths in population

Question 20

Standardized morality ratio (SMR)

Answer 20

of causes specific deaths/expected total # of deaths from a similar population

Question 21

Induction

Answer 21

Infectivity periods

infected/ # susceptible

Question 22

Latency

Answer 22

pathogenicity periods

with clinical disease / # of infected