Measures of Association Flashcards
Absolute difference
subtraction
group 1 = 135
group 2 = 25
group 1 had 110 more outcome occurrences
group 2 had 110 less outcome occurrences
Relative frequency
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
Risk Ratio: probability of outcome in exposed, Risk in exposed
A / (A+B)
Risk Ratio: probability of outcome in non-exposed, Risk in non-exposed
C/(C+D)
Incidence Risk (IR)
Risk Ratio
Risk in exposed
Risk in non-exposed
Absolute Risk Reduction
IR G1 - IR G2
if risk is 1.5 in exposed and 1.2 in nonexposed,
1.5-1.2 = answer
Relative Risk Reduction
Absolute Risk Reduction/R in unexposed
NNT & NNH
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.
Odds of exposure in cases
A/C
Odds of exposure in controls
B/D
Odds ratio
(A/C) / (B/D)
crude morbidity rate
of persons with disease / # in population
crude mortality rate
of deaths / # in population
Cause specific mortality rate
of cause specific deaths / # in population
Case-fatality rate
of cause specific deaths / # of cases of disease
Cause-specific survival rate
of cause-specific cases alive /# of cases of disease
Live birth rate
of births / 1000
Fertility rate
of live births / 1000 women of childbearing age
Proportional mortality ratio
of causes specific deaths/ total # of deaths in population
Standardized morality ratio (SMR)
of causes specific deaths/expected total # of deaths from a similar population
Induction
Infectivity periods
infected/ # susceptible
Latency
pathogenicity periods
with clinical disease / # of infected
