What is boundary setting
action of precess of determining and enacting selection criteria for study participants, study concepts or study phenomena
What are guidelines for determining inclusion/exclusion criteria?
- Appropriateness - the extent to which the inclusion/exclusion criteria fit the overall purpose of the study – determined by research design, problem, purpose and structure
- Adequacy - the extent to which the inclusion/exclusion criteria yields sufficient data to answer the research problem
Saturation of data - qualitative
Sample size calculation - quanitative
What are the steps of sampling in quantitative studies?
- Define population
- develop sampling plan
- determine sample size
- implement sampling procedures
- compare critical values of sample to population
What is probability sampling?
based on probability theory:
- parameters of population are known
- every member or element has equal probability of being selected
**Preferred for quantitative studies, higher external validity, can be impractical
What are probability sampling examples?
- SIMPLE RANDOM SAMPLING: ex. drawing from a hat
- SYSTEMATIC SAMPLING: determining a sampling interval width based on the needed sample size, then selecting every ___ element from a sampling frame
- STRATIFIED RANDOM SAMPLING:
- CLUSTER SAMPLING
What is non-probability sampling?
sample is not chosen on the basis of equal chance to be selected from a population
**used when not feasible to develop a sampling frame, easier to conduct
What are non-probability sampling examples?
- CONVENIENCE SAMPLING - involvement of available subjects
- PURPOSIVE SAMPLING - deliberate selection of individuals by researcher on the basis of predefined criteria
- SNOWBALL SAMPLING - asking subjects to provide access to others who may meet the criteria
- QUOTA SAMPLING
What are ways to set boundaries in qualitative studies?
- geographical location/physical setting
- cultural group
- personal experience
What are strategies for sampling?
- Maximum variation: seeking individuals who are extremely different along dimensions that are the focus of the study
- Homogenous selection: choosing participants w/similar experiences
- Theory based selection: choosing participants who exemplify a particular theoretical construct
- Confirming or disconfirming cases: finding informants who will either support or challenge the emerging theory
- Extreme case: select case that represents an extreme example of the phenomenon
- Typical case: typical cases that characterize a phenomenon
