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PHC 6013: Sample
Choosing the study subjects: Specification, sampling, and recruitment
Term | Definion |
---|---|
Population | A complete set of people with a specified set of characteristics |
Study sample | The subset of the accessible population that participates in the study |
Characteristics that define a population | 1) Geography 2) Clinical 3) Demographic 4) Temporal |
Target population | Defined by clinical and demographic characteristics. The large set of people throughout the world to which the results will be generalized. |
Accessible population | A geographically and temporally defined subset of the target population that is available for study |
Inclusion criteria | Define the main characteristics of the target population that pertain to the research question |
Exclusion critera | Indicate subsets of individuals who would be suitable for the research question were it not for characteristics that might interfere with the success of follow-up efforts, the quality of the data, or the acceptability of randomized treatment |
What is a drawback of using hospitalized or clinic-based patients? | Patients tend to have serious forms of the disease that give a distorted impression of the commonplace features and prognosis. Sampling from primary care clinics can be a better choice. |
What is a drawback of selecting a sample from the community? | They are not representative of a general population because they: 1) Volunteer 2) Fit inclusion and exclusion criteria 3) Agree to be included in the study |
Convenience sample |