Nursing 360: Sampling Methods and Statistics

Random (Probability) sampling

• A selection process that ensures each participant the same probability of being selected.
• The best method for ensuring that a sample is representative of the larger population.
• Random sampling can be:
  • simple random sampling
  • stratified random sampling, or
  • cluster sampling

Nonprobability sampling

• The probability that any one individual or subject is selected is not equal to the probability that any other individual or subject may be selected.
• Probability of inclusion and the degree to which the sample represents the population are unknown.
• Major problem is that sampling bias can occur.
• Nonprobability sampling can be:
  • convenience sampling
  • purposive sampling, or
  • quota sampling

Nursing Planet

• Open access articles on nursing research.
• Includes practice quizzes on many aspects of research: sampling, statistics, study designs, etc.

• An instrument in a research study is a device used to measure the concept of interest in a research project.
• An ideal measuring instrument is one which results in measures that are relevant, accurate, objective, sensitive and efficient.
• Measures which are physical and physiological have higher chance of success in attaining these goals than measures that are psychological and behavioral.
• Instruments may be:
  • observation scales
  • questionnaires, or
  • interview schedules
• Validity and reliability are two statistical properties used to evaluate the quality of research instruments
• It is important that assessment techniques possess both validity and reliability (Anastasi, A. 1986. Psychological testing. NY: Macmillan).

While "population" is about the generality of the universe or groups of people, "sample" refers to a fraction of persons from the population.

It is from the sample that data are collected in the course of a study, and if that sample is representative of the population, the results can be generalized to the population in a scientific study.

Quantitative, Qualitative, Mixed Methods

Statistics Made Easy (8-part video series)

• See especially Parts 1, 3, 4.