Research Methodology: Sampling Techniques

Research Methodology

• Individuals are the most common source of evidence in research, often called participants or subjects.
• A sample is the collective group of individuals from whom data are collected.
• Probability sampling is a sampling procedure in quantitative research where the probability of selecting a participant is known, and a sample representative of a larger group is aimed for.
• Non-probability sampling is another sampling procedure where there is no known probability of selecting a participant.
• The margin of error in sampling is the extent to which repeated random samples will deviate from the population.
• The margin of error decreases as the sample size increases.
• Simple random sampling, systematic sampling, stratified random sampling, and cluster sampling are random sampling techniques.

Sampling Techniques

• Simple random sampling: Every member of the population has an equal chance of being selected.
• Systematic sampling: Selecting every nth member of a list or population.
• Stratified random sampling: Subgroups within a population are proportionally represented in the sample.
• Cluster sampling: Naturally occurring groups are randomly selected, then subjects are randomly selected from those groups.

Sampling Procedures (Qualitative and Quantitative)

• Convenience sampling is when the ease of recruiting participants is the primary factor for participant selection.
• Snowball sampling is when participants are asked to recommend other participants.
• Extreme case sampling selects unique/atypical outliers.
• Purposeful sampling selects participants to provide the best information to address a research question, studying these cases in depth.

Literature Reviews

• A literature review relates previous research and theory to a problem under investigation.
• A literature review helps place a research problem in context by comparing and contrasting the current or proposed study to previous investigations.
• A literature review helps to identify methodological limitations of previous research.
• Identifying contradictory findings in previous research can help formulate a new research design.
• Literature helps resolve research contradictions.
• Existing theories can justify research hypotheses when there are few related studies.
• Literature reviews can help refine research questions and define conceptual or theoretical orientations
• Literature reviews help researchers avoid duplication by revealing what has already been studied and identifying gaps in the existing literature.

Types of Tests

• Norm-referenced tests compare scores to others.
• Criterion-referenced tests compare scores to a fixed standard.
• Standardized tests include achievement tests (knowledge), aptitude tests (future performance), and standards-based tests (specific benchmarks).
• Characteristics of tests are: norm-referenced vs. criterion-referenced, achievement vs. aptitude, standardized vs. locally developed.

Types of Scales

• Likert scales measure agreement levels.
• Semantic differential scales use bipolar adjectives to measure attitudes

Data Collection Methods

• Questionnaires collect large quantities of data quickly.
• Questionnaires can be prone to bias.
• Interviews are good for rapport building, they can gather in-depth data, and are flexible.
• Interviews can be time-consuming and costly.
• Double-barreled questions combine two issues in one question, causing ambiguity.
• Observations can be either low-inference or high-inference.
• Low-inference requires minimal interpretation, while high-inference requires judgment.
• Challenges for high inference are observer bias and reliability issues.
• Reducing observer bias: Training, using multiple observers, ensuring observers are blind to hypotheses.

Phenomenological Research

• Phenomenological research is about the study of lived experiences.
• In phenomenological research, the lived meaning of an experience should be described.
• In phenomenological research, avoiding generalization is important.

Research Ethics

• Informed consent is required for participants in all research studies.
• Ensuring ethical integrity in research involves protecting participants' anonymity and confidentiality.
• Institutions Review Boards review research proposals to ensure ethical standards are upheld before data collection begins.