Research Methods and Sampling Techniques

Study Notes

A variable is anything that can change or vary.
Quantitative variables are measured numerically and can be reported using statistics like frequency, mode, median, and mean.
Qualitative variables are described using words and involve categories.
An operational definition clearly describes exactly how a variable will be measured.
Sampling methods determine how researchers select participants to represent a larger population.

Simple random sampling gives each individual an equal chance of being selected.
Stratified random sampling divides the population into subgroups and then randomly selects participants from each subgroup.
Cluster random sampling uses randomly selected subgroups where every member of each selected subgroup is included in the study.
Systematic random sampling involves selecting the first participant randomly and then choosing every nth participant after that.
Convenience sampling uses readily available participants.
Voluntary response sampling relies on participants self-selecting to participate.
Snowball sampling uses referrals from existing participants to recruit more participants.

Statistical relationships occur when two variables vary together systematically.
Differences between groups are often shown using bar graphs and involve comparing means or medians of variables.
Correlations between quantitative variables are presented using scatterplots.
Positive relationships show higher scores on one variable associated with higher scores on the other.
Negative relationships show higher scores on one variable associated with lower scores on the other.
Pearson's r measures the strength of a linear correlation between quantitative variables. A value of +1.00 represents the strongest positive relationship, -1.00 represents the strongest negative relationship, and 0 represents no relationship.
Correlation does not equal causation.

Independent variable is manipulated by the researcher and is thought to cause change in the dependent variable.
Dependent variable is the outcome variable being measured and affected by the independent variable.
Directionality problem makes it difficult to determine whether X causes Y or Y causes X.
Third-variable problem suggests a third variable Z could be influencing both X and Y.

Generating interesting research questions involves finding gaps in the literature and considering their practical applications.
Feasibility depends on available resources, time, equipment, expertise, and access to participants.

Research literature encompasses all published research in a specific field.
Empirical articles, review articles, and theoretical articles are common types found in professional journals and scholarly books.
Double-blind peer review ensures quality and impartiality in scientific publications.
Monographs provide coherent presentations of a topic by a single author or group.
Edited volumes are collections of chapters by different authors on various aspects of a topic.