Apply What You Have Learned
As your EBP committee has progressed in its assignment to identify strategies to improve hand
hygiene compliance, you have been challenged to apply research principles for the purpose of
establishing best practices. The next step is to review your articles, paying particular attention to
details about the sample. Fill in the column for population on your grid by including details such
as sample characteristics, sampling method, and size. Consult the examples already done.» Sampling methods are determined by the research purpose and the research design.
» There are two major types of sampling: probability and nonprobability.
» Probability sampling and selected nonprobability sampling are used in quantitative research.
Fundamental to probability sampling, but not nonprobability sampling, is random selection
of subjects.
» Probability sampling methods include simple random sampling, stratified random sampling,
cluster sampling, and systematic random sampling.
» Nonprobability sampling methods include convenience sampling, quota sampling, purposive
sampling, and theoretical sampling.
» In quantitative research, the goal of sampling is to select a representative sample by identify-
ing subjects that reflect the same characteristics as the population.
» The more representative the sample, the more confidence there is generalizing to the population.
» Nonprobability sampling is used in qualitative research.
» Sample size is determined by homogeneity of the population, purpose of the study, attrition
rate, design, number of variables being investigated, and the sensitivity of instruments used.
» Power analysis is used to calculate the minimal number of subjects required in a quantita-
tive study.
» Sample size for qualitative research continues until saturation is achieved.
» When making decisions about EBP, critical appraisal of the sampling method and sample
size is desirable.
» Researchers must attend to many factors to ensure that the rights of subjects are protected.
Researchers must ensure that informed consent is obtained and that individuals choose freely,
without coercion, to participate in studies.
» Vulnerable populations must be especially protected by researchers.RAPID REVIEW
306 CHAPTER 11 Using Samples to Provide Evidence