| Study type |
Characteristics |
Advantages |
Disadvantages
|
| Descriptive
|
* Observational * Describe patterns of disease in the population
|
* Relatively quick and easy * Can generate hypotheses on possible risk factors for further investigation * Doesn't require random sampling or high degree of rigour
|
* Doesn't support hypothesis testing or inference for possible risk factors * Can't estimate prevalence or incidence or exposure proportions * Subject to inherent biases and errors because of the nature of the data
|
| Cross-sectional
|
* Observational * Observation at point in time * Outcome/exposure not considered in selection
|
* Disease prevalence in exposed and unexposed populations can be estimated * Exposure proportions can be estimated * Relatively quick and cost-effective * Can study multiple factors at once
|
* Unsuited to investigating rare diseases * Less useful for acute diseases * May be difficult to control potential confounders * Incidence cannot be estimated * May be difficult to determine causality * May be problems with reliability of data/recall for historical data
|
| Case-control
|
* Observational * Retrospective longitudinal * Selection based on outcome status
|
* Good for rare diseases * Relatively rapid and cost-effective * Relatively small sample sizes * Often use existing data * Can study multiple factors at once
|
* May be difficult to establish causality * Can't estimate prevalence or incidence or exposure proportions * Rely on access to historical data or recall * Difficult to validate data * May be affected by variables for which data is not collected * Selection of controls often difficult
|
| Cohort
|
* Observational * Prospective longitudinal * Selection based on exposure status
|
* Can calculate incidence in exposed and unexposed individuals * Can provide strong evidence for causality
|
* Exposed/unexposed proportions cannot be estimated * Large sample sizes, particularly for rare diseases * Can only investigate small number of potential risk factors at any one time * Long duration of follow-up * Relatively expensive and time-consuming * Loss of individuals to follow-up * May be difficult to control potential confounders
|
| Field/clinical trials
|
* Intervention * Longitudinal * Randomised selection
|
* Relatively quick * Good for helping establish causation * Usually strong internal validity * Relatively small sample size and usually short duration * Can't estimate incidence/prevalence
|
* May be problems with external validity, particularly to diverse target population * Can be expensive depending on the intervention and situation * Requires significant cooperation and rigorous management
|
