Alternative Hypothesis
The alternative hypothesis, denoted H1 or Ha, is the statement that an effect, difference, or relationship between variables exists in the population being studied.
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Research Glossary
Every term defined with cited sources, real world examples, interactive learning, and the methodological depth that serious research demands.
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Research Methodology Terms
The foundations of doing research well: research questions, hypotheses, variables, validity, sampling, bias and research ethics. Start here to understand the decisions that shape any study, whatever the field or design.
A
Applied Research
Applied research is investigation conducted to solve a specific, practical problem or to develop actionable knowledge for a defined context, rather than to advance understanding of abstract phenomena.
Archival Research
Archival research is a method of inquiry that involves analyzing existing records, documents, or datasets that were originally created for purposes other than the current study.
Attrition
Attrition refers to the loss of participants from a study over time due to withdrawal, dropout, loss to follow up, death, or other reasons.
Attrition Bias
Attrition bias is a systematic error that arises when participants who drop out of a study before completion differ in meaningful ways from those who remain, creating differences between groups that are not attributable to the intervention.
B
Basic Research
Basic research, also called pure or fundamental research, is investigation aimed at increasing understanding of underlying principles and phenomena without immediate practical application in mind.
Bias
Bias is a systematic error in the design, conduct, analysis, or reporting of a study that produces results that consistently deviate from the truth in a particular direction.
C
Causal Inference
Causal inference is the process of drawing conclusions about cause and effect relationships from data, using study design features, statistical methods, and theoretical reasoning to distinguish genuine causation from mere correlation or confounded…
Conceptual Framework
A conceptual framework is a visual or written representation of the key variables, constructs, and their expected relationships in a study.
Conflict of Interest
A conflict of interest in research occurs when a researcher's financial, personal, professional, or institutional interests could compromise, or reasonably appear to compromise, the integrity, objectivity, or ethical conduct of their work.
Confounding Variable
A confounding variable is an extraneous factor that is associated with both the independent variable and the dependent variable in a study, distorting the true relationship between the variables of interest by creating, exaggerating or masking an association.
Construct Validity
Construct validity refers to the degree to which a measurement instrument accurately captures the theoretical concept, or construct, it is intended to measure.
Convenience Sampling
Convenience sampling is a nonprobability sampling method in which participants are selected based on their accessibility and willingness to participate rather than through random selection from a defined population.
Critical Theory
Critical theory is a research paradigm and intellectual tradition concerned with power, inequality, and social justice, originating from the Frankfurt School of social thought in the 1930s (Max Horkheimer, Theodor Adorno, Herbert Marcuse, and later Jürgen…
Cross Cultural Research
Cross cultural research is a systematic approach to comparing phenomena across different cultural groups, examining how cultural context shapes behaviors, beliefs, attitudes, or outcomes.
D
Data Fabrication
Data fabrication is the intentional creation of data, results, or experimental observations that were never actually collected, measured, or observed, and their presentation as genuine research findings.
Deception in Research
Deception in research is the deliberate withholding of information from, or provision of misleading information to, research participants about some aspect of the study, including its purpose, procedures, or the nature of the stimuli being presented.
Dependent Variable
The dependent variable is the variable in a research study whose value is expected to change in response to the manipulation or variation of one or more independent variables.
Detection Bias
Detection bias refers to systematic differences between study groups in how outcomes are identified, measured, or assessed.
E
Empirical Research
Empirical research is research based on observed and measured phenomena, deriving knowledge from direct or indirect observation and experience rather than from theory, authority, or speculation alone.
Exploratory Research
Exploratory research is a preliminary form of investigation conducted to clarify the nature of a problem, generate hypotheses, or identify variables for further study.
External Validity
External validity is the extent to which the results of a study can be generalized or applied to other settings, populations, time periods, or conditions beyond the specific context in which the study was conducted.
F
Field Study
A field study is a research investigation conducted in a natural, real world setting rather than in a laboratory or otherwise controlled environment.
Formative Research
Formative research is investigation conducted during the development phase of an intervention, program, or policy to inform its design, refine its components, and identify potential barriers to implementation.
G
Generalizability
Generalizability is the extent to which findings from a specific study can be applied to the broader target population, other settings, other time periods, or other conditions beyond those directly examined.
Good Research Practice
Good Research Practice (GRP) is a set of principles and standards governing the ethical and scientific quality of research across all disciplines.
H
Helsinki Declaration
The Declaration of Helsinki is a statement of ethical principles for medical research involving human participants, adopted by the World Medical Association (WMA) in 1964 and revised multiple times since, most recently in October 2024.
Human Subjects Research
Human subjects research is research that involves living individuals, either through intervention or interaction with them or through identifiable private information or biospecimens about them.
Hypothesis
A hypothesis is a testable, falsifiable statement that predicts the relationship between two or more variables.
I
Immortal Time Bias
Immortal time bias is a form of selection bias in observational studies that occurs when the period between cohort entry and the start of exposure includes a span of time during which the outcome of interest could not have occurred.
Independent Variable
The independent variable is the factor that is systematically manipulated, controlled, or measured by the researcher to examine its effect on the dependent variable.
Informed Consent
Informed consent is the process by which a prospective research participant voluntarily agrees to take part in a study after receiving a thorough explanation of the study's purpose, procedures, potential risks and benefits, alternatives to participation, and…
Institutional Review Board (IRB)
An institutional review board (IRB) is an ethics committee, set up by a research institution or operating independently, that reviews, approves, and monitors research involving human subjects.
Internal Validity
Internal validity is the degree to which a study accurately establishes a causal relationship between the independent variable and the dependent variable, free from the influence of confounding variables, biases, or other systematic errors.
Interpretive Framework
An interpretive framework is the set of philosophical assumptions, beliefs, and theoretical perspectives that guide a qualitative researcher's approach to inquiry, shaping decisions about research design, data collection, analysis, and interpretation.
J
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P
Paradigm
A paradigm is a broad framework of assumptions, concepts, values, and practices that constitutes a way of viewing reality for the community that shares it.
Performance Bias
Performance bias refers to systematic differences in the care provided to participants in a study, apart from the intervention being evaluated, that arise because participants, clinicians, or other providers know which treatment group a participant belongs…
PICO (Population, Intervention, Comparison, Outcome)
PICO is a framework used to formulate focused clinical and research questions by specifying four key components: the Population (who is being studied), the Intervention (what treatment or exposure is being examined), the Comparison (what alternative is being…
Population
In research, a population is the entire group of individuals, objects, events, or measurements about which a researcher wishes to draw conclusions.
Probability Sampling
Probability sampling is a sampling method in which every member of the target population has a known, nonzero probability of being selected for the study.
Protocol
A protocol is a detailed, prespecified plan for conducting a research study or systematic review, written in advance of data collection to define the research question, study design, methods, eligibility criteria, data collection procedures, and statistical…
Q
R
Regression to the Mean
Regression to the mean is a statistical phenomenon in which extreme values on a first measurement tend to be closer to the population average on subsequent measurements, regardless of any intervention applied between the measurements.
Replication
Replication is the process of repeating a study using similar or identical methods to determine whether the original findings can be reproduced. Direct replication uses the same methods, procedures, and conditions as the original study.
Research Ethics
Research ethics encompasses the principles, standards, and practices that govern the responsible conduct of research, ensuring the protection of human participants, the integrity of the scientific record, and the responsible use of research resources.
Research Gap
A research gap is an area within the existing body of literature where knowledge is incomplete, contradictory, outdated, or entirely absent, indicating that further investigation is needed.
Research Question
A research question is a clear, focused, and answerable question that defines the purpose and direction of a study, determining its design, methodology, data collection, and analysis.
Research Waste
Research waste refers to the expenditure of scientific resources on studies that fail to produce usable, accessible, or relevant knowledge due to problems in design, conduct, analysis, reporting, or dissemination.
S
Sample
A sample is a subset of individuals, observations, or data points selected from a larger population for the purpose of conducting a study.
Selection Bias
Selection bias is a systematic error that arises when the way participants enter or stay in a study distorts its estimate of an association or effect.
Snowball Sampling
Snowball sampling is a nonprobability sampling method in which existing study participants recruit additional participants from their social networks, creating a chain of referrals that expands the sample.
Stratified Sampling
Stratified sampling is a probability sampling technique in which the target population is divided into mutually exclusive, exhaustive subgroups (strata) based on a characteristic relevant to the research question, and a random sample is drawn independently…
T
V
Validity
Validity in research refers to the degree to which a study, measurement, or inference accurately reflects or measures what it is intended to measure or assess. Validity is not a single property but rather a multifaceted concept with several distinct types.
Variable
A variable is any characteristic, property, or attribute that can take on different values or categories across observations, participants, or experimental conditions.