Study designs in epidemiology
- Created by: Sophie
- Created on: 24-10-18 12:57
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- Research studies used in cancer epidemiology
- Cohort study
- a cohort is a group of people that share a common experience
- follows a cohort of people over a period of time to see how exposure influences the outcome
- all of the people that are recruited at the start of the study don't have the disease of interest
- the group is split into a group of exposure or non-exposure and then are monitored over a period of time to see who develops the outcome of interest
- it is one of the most common forms of study that is chosen in cancer epidemiology
- take place over a long period of time so there can be loss to follow up - non participation bias
- Case - Control study
- cases are selected from a group of individuals that have the disease of interest
- a group of suitable controls are then selected to compare the cases to
- looks at the relationships between outcome and exposure
- cases are selected from a group of individuals that have the disease of interest
- looks at the relationships between outcome and exposure
- controls can only be selected if they would have been included in the study if they had had the disease
- it is one of the most common forms of study that is chosen in cancer epidemiology
- it is retrospective so it is worked back to find out the exposure that had caused the disease
- but cases can be added prospectively, as new cases are diagnosed they are added into the cases group
- directionality can be determined as you know that the exposure must have happened before the disease
- timing can be determined
- matching can be used to control for confounding variables
- environmentalstudy
- observational study that looks at population data rather than individual data
- used when there is no individual data available or there is too little for the data to remain anonymous as individual data
- care needs to be taken when applying group findings to an individual as ecological fallacy can be introduced
- can be used to make large scale comparisons between countries
- longitudinal study will follow a population over a period of time and assess the changes
- there may be unknown confounding factors that may display the same pattern of disease
- ecological fallacy is only seen in ecological studies and occurs when relationships found for groups are assumed to be true for individuals
- Cross sectional study
- observational studies that look at the prevalence of disease at one point in time
- provides a indication of the risk factors and associated outcomes at that time
- there is no loss to follow as it is only looked at at one point in time
- used when the purpose of the study is descriptive
- there is usually no prior hypothesis for this type of study but can be used to generate hypothesis
- helps with public health interventions
- can't infer causal associations
- no indication of the sequence of events
- some people may be more likely to respond than others so might be biased responses
- observational studies that look at the prevalence of disease at one point in time
- Cohort study
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