200370
Description
Mind Map by shirley.ha, updated more than 1 year ago
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Created by shirley.ha
over 11 years ago
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Odds Ratio
- similar to RR but...
- 1. Is used mainly to analyse data from case-control studies.
- 2. Gives an approximation to the RR
- 3. Is used when RR is inappropriate (e.g., when examining
rare diseases in the population using case-control designs).
- 4. Both OR and RR are also accompanied by confidence intervals.
- 1. Is used mainly to analyse data from case-control studies.
- ratio of the odds of exposure among cases to the
odds of exposure among the controls.
- why we use it?
- Because RR cannot be calculated in
case-control studies, because these studies
usually examine rare and uncommon
diseases
- Unlike a cohort study, we do not know
the risk for exposure in the population
- Because RR cannot be calculated in
case-control studies, because these studies
usually examine rare and uncommon
diseases
- Interpretation
- used to calculate risk from case-control
studies but if the study is done well (that
is, bias is limited as much as possible
and the disease is rare),
- valid measure of association
that approximates the RR from
a cohort study
- valid measure of association
that approximates the RR from
a cohort study
- used to calculate risk from case-control
studies but if the study is done well (that
is, bias is limited as much as possible
and the disease is rare),
- the larger the OR, the stronger the
association between the disease and the
exposure
- Confidence Intervals
- provide information about the
precision of the association.
- provide information about the
precision of the association.
- CORRELATION CO-EFFICIENT
(r)- Measures of assoc btwn the
two variables
- statistical measurement describing the
degree and strength of the association
between two continuous variables
- Correlation rules
- r=0
- is no association between the variables
- is no association between the variables
- r=1
- perfect +ve correlation, meaning that
both variables move in the same
direction together.
- perfect +ve correlation, meaning that
both variables move in the same
direction together.
- r=-1
- perfect -ve correlation,
meaning that as one
variable goes up, the
other goes down
- perfect -ve correlation,
meaning that as one
variable goes up, the
other goes down
- r=0
- measures the degree to which
values for two measures move
together in a synchronised manner
- r closer 0- INDEPENDENT
- CLOSER TO ONE ANOTHER- DEPENDENT
- CLOSER TO ONE ANOTHER- DEPENDENT
- r closer 0- INDEPENDENT
- 2 ASPECTS
- Strength
- Direction
- Strength
- correlation by itself does not imply causation
- correlations assess the strength of
associations.
- correlations assess the strength of
associations.
- statistical measurement describing the
degree and strength of the association
between two continuous variables
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