Population and Social Science Flashcards
Name the 4 types of observational studies.
- Descriptive
- Cross-sectional
- Ecological
- Analytical
- Case-control
- Cohort
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Describe how an ecological study is conducted.
- Population level (group analysis)
- Observational
- Ecological fallacy (inference made about individuals from group data collected)
(Ecological fallacy= type of confounding variable)
Describe a cross-sectional survey/study.
- Measures exosure and disease- one point in time
- Data from individuals
Define prevalence and incidence rate.
Prevalence: Existing cases as proportion of population
Incidence rate: New cases in population per year (Person-years)
What can prevalence and incidence rate be used to measure?
Absolute risk (of event happening)
What is an incidence rate ratio?
Compares incidence rate of 2 populations
Is exposure associated with condition?
What is the difference between incidence rate ratio and risk ratio?
Incidence rate ratio= incidence rate
Risk ratio= prevalence
Identify a solution to limit the effect of confounding variables in a study.
- Selection (match confounders)
- Calculations (standardisation, stratifying etc)
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What is the standardised mortality ratio?
SMR: Observed/expected deaths x 100
What does a SMR> 100 suggest?
Excess mortality with confounders accounted for
When measuring mortality rate, what’s the difference between direct and indirect standardisation?
Direct= uses reference population (same population numbers)
Indirect= uses mortality rates from one population to another (observed and expected deaths)
What is the sampling frame?
List or method through which sample= obtained
(assumed to be representative of population)
Why do we use an Error Factor (EF) with epedimiological studies?
- True value of population= different to sample
- Error factor used to help infer true value
- Size of EF depends on size of population
What is the confidence interval?
(Use EF to work out CI)
Interval where the true value lies
(which we can say with 95% confidence)
What are the 2 types of validity a study must have?
- Internal validity
- Freedom from confounding, bias, random error
- External validity
- Degree to which conclusions from study can be applied to population of interest