CH 9 Flashcards
Population
A particular group of individuals or elements who are the focus of the research
Target population
An entire set of individuals or elements who meet the sampling criteria
Accessible population
The portion of the target population to which the researcher has reasonable access
Sample
Defines the selected group of people or elements from which data are collected for a study
Sampling
Selection of a subset of a population to represent the whole population
Inclusion Criteria
Characteristics that the subject or element must possess to be part of the target population
Exclusion Criteria
Characteristics that can cause a person or element to be excluded from the target population
Representativeness
the sample, access population, and target population are alike in as many ways as possible
Generalization
Extending the findings from the sample under study to the larger population.
- The extent is influenced by the quality of the study and consistency of the study’s findings.
Sample Size in Quantitative Studies
Effect size: the size of difference between the groups or the strength of the relationship between two variables.
- Number of variables
- Measurement sensitivity
- Data analysis techniques
Sample Size in Qualitative Research
Saturation: occurs when additional sampling provides no new information, only redundancy of previous collected data.
- Scope of the study
- Nature of the topic
- Quality of the data
- Study design
Probability Sampling (Generalizability ↑)
Random !
- Simple random sampling
- Stratified random sampling
- Cluster sampling
- Systematic sampling
Simple Random
Most basic of the probability sample plans. It is achieved by randomly selecting elements from the sampling frame.
Stratified Random
Used in situations in which the researcher knows some of the variables in the population that are critical for achieving representative.
Variables commonly used age, gender, race, and ethnicity
Cluster Random
Researcher develops a sampling frame that includes a list of all the states, cities, institutions, or clinicians with which elements of the identified population can be linked.
Systematic Random
Used when an ordered list of all members of the population is available.
Nonprobability Sampling (Generalizability ↓)
- Convenience
- Purposeful
- Theoretical
- Network
- Quota
Convenience
Also called accidental sampling, is a relatively weak approach because it provides little opportunity to control biases; participants are included in study merely because they happen to be in the right place at the right. time.
Purposeful
Sometimes referred to as judgmental or selective sampling, the researcher consciously selects certain participants, elements, event, or incidents to include in the study.
Theoretical
Used in qualitative research to develop a selected theory or model through the research process. This type is used most frequently with grounded theory research.
Network
Sometimes referred to as snowball, chain, or nominated sampling, holds promise for locating participants who would be difficult or impossible to obtain in other ways or who had not been previously identified for study.
Quota
Uses a convenience sampling technique with an added feature– a strategy to ensure the inclusion of participant types likely to be underrepresented in the convenience sample (e.g. women, minorities).
Sample Size Calculation in Quantitative Study
- Small effect size <0.30 or 0.50 or >- 0.50
Sample Size Calculation in Qualitative Study
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