analytical studies and key statistical concepts Flashcards
what design are epidemiological study
obersavtional
why do we do epidemiological studies?
- Understand what happened
- Estimate the extent of the outbreak
- Identify the potential source
- Can be controlled and prevented in the future
- Create evidence and knowledge
what is descriptive epidemiology
identify a potential source of the disease as well as likelihood of an exposure is associated with the disease.
when was the population affected, who was affected
what is risk
proportion of initially disease-free individuals who develop a disease over a defined period of observation
when would you use a cohort study
in a well-defined population where they all have something in common such as exposure
what is attack risk
proportion of people who become ill with a disease in a population initially free of the disease
when is a case control study used
when there is not a defined population, all cases are included and then controls are selected
what is an odds ratio
estimates the difference of frequency of exposure between cases and controls
what relative risk RR is a risk factor:
RR greater than 1
what relative risk has no association
when RR = 1
what is a relative protective factor
when RR = <1
examples of when case control outbreaks used
take-aways, most outbreaks, pandemics
what are P-values
probability of obtaining the results at least as extreme as the observed results assuming the null hypothesis is correct
what is a statistically significant P value
<0.05
what is a statistically insignificant P value
> 0.05
what are confidence intervals
range of potential values for the risk ratio or odds ration.
what does a 95% CL including 1 mean?
the data is not relevant
what is univariable analysis
one exposure variable
what is a confounder
something that is associated with both exposure and outcome
what is multivarible analysis
looking at associations for several X variables (exposures) simultaneously but only one Y variable (illness)
what are the aims of multivariable analysis
- understand what variables are associated with an outcome
- account for the effect of other variables when measuring one variable
- adjust for confounders
when is odds ratio used
when we don’t know the whole population, case-control studies
examples of when cohort studies would be used
weddings, functions
what is Analytical epidemiology
looks at how and why the population were affected
