EH1 Week 4 Flashcards
what are the 2 classifications of studies
qualitative
- larger population
- results are assessed using statistical methods
quantitative
- smaller population
what are the 2 types of quantitative studies
descriptive and analytical
what are the subcategories of descriptive studies and their main features
case study
- study of one patient
- May generate a hypothesis about an association between exposure and disease
case series
- Small collection of cases with common characteristics
- Also generates a hypothesis about exposure and disease
cross sectional survey
- analyses data from a population at a single point in time
what are some features of descriptive studies
o Cannot quantify the relationship between factors, only describes what is happening
o Used to generate a hypothesis
o Cannot prove or confirm hypotheses
what are some features of analytical studies
o Used to test hypothesis or causal relationships
o Assesses the relationship/association between a study factor and an outcome
what are the types of analytical studies
case control study and cohort study
what is a case control study
- Disease present = case
- Disease or no disease is the study factor
Exposure is the outcome of interest - Case-control studies are always retrospective, because they start with the disease.
what is a cohort study and its subcategories
- Disease absent = control
*. Exposure is the study factor, disease is the outcome of interest - retrospective and prospective
what is a retrospective cohort study
Uses existing data that was collected in the past.
outcome has already occurred
no future follow up
what is a prospective cohort study
the study proceeds forward in time. Looks for
disease occurring in the future.
includes randomized control trial which is the only interventional study
what are the 3 types of bias
selection bias, information bias and confounding
what is a section bias
- the way that people are selected
into the study distorts the estimate of association
what is information bias
- Occurs when information is collected
differently between two groups leading to an error in making an association. People may recall exposure more if they have the disease
what technique can be used to prevent information bias
blinding
what is confounding
- occurs where an apparent association between a presumed exposure and an outcome is accounted for by a third variable.
what can cause random error and what reduce the effects of this
- Can occur if the sample size is too small
- Increasing the size of the study by increasing the number of participants will reduce the effect of random error
what is epidemiology and its two categories used to determine it
the study of disease frequency
incidence and prevalence
what is incidence
number of new cases arising in a given period of time
tells us the number of people at risk of the event or the disease happening (time must be mentioned)
what is age standardizing
can be used to prevent age structure being a confounding factor
what is prevalence
looks at the number of existing cases in a given period of time (%)
Used for chronic stable disease and not acute conditions like the flu
