Research Glossary

A systematic investigation designed to develop or contribute to generalizable knowledge through careful observation, experimentation, and analysis.

A testable statement or prediction about the relationship between two or more variables, formulated before data collection begins.

Any characteristic, number, or quantity that can be measured, manipulated, or controlled in a study. Variables can be independent (manipulated), dependent (measured), or confounding (uncontrolled).

A subset of individuals selected from a larger population to participate in a study. The sample should be representative of the population to allow generalization of findings.

The entire group of individuals or observations that share a common characteristic and to whom the research findings are intended to apply.

A systematic error that leads to incorrect or misleading results. Bias can occur at any stage of research including design, data collection, analysis, or interpretation.

The process of randomly assigning study participants to different groups (e.g., treatment vs. control) to minimize selection bias and ensure groups are comparable at baseline.

A technique where participants, researchers, or both are kept unaware of group assignments to prevent bias in treatment delivery and outcome assessment. Single-blind means participants are unaware; double-blind means both participants and researchers are unaware.

A group of participants in an experiment that does not receive the intervention or treatment being tested, serving as a baseline for comparison with the experimental group.

The process by which a participant voluntarily agrees to take part in research after being fully informed about the study's purpose, procedures, risks, benefits, and alternatives.

A detailed written plan that describes the objectives, design, methodology, statistical considerations, and organization of a research study.

An extraneous variable that correlates with both the independent and dependent variables, potentially distorting the true relationship between them.

A detailed report of the symptoms, diagnosis, treatment, and follow-up of an individual patient. It is the lowest level of evidence but valuable for documenting rare conditions or novel findings.

A descriptive study that tracks a group of patients with a similar diagnosis or treatment over time, without using a control group.

An observational study that collects data from a population at a single point in time to examine the prevalence of a disease or the relationship between variables.

An observational study that follows a group of people over time to determine how certain exposures or characteristics affect the occurrence of an outcome.

An observational study that compares individuals with a disease or outcome (cases) to similar individuals without the disease (controls), looking backward to identify potential risk factors.

An experimental study design where participants are randomly assigned to an intervention group or a control group, considered the gold standard for evaluating treatment efficacy.

A rigorous, structured review of all available evidence on a specific research question, using predefined criteria to identify, select, appraise, and synthesize relevant studies.

A statistical technique that combines results from multiple independent studies addressing the same question to produce a single, more precise estimate of effect size.

A comprehensive but non-systematic summary of the literature on a particular topic, typically written by experts. Unlike systematic reviews, the selection criteria are not predefined.

Research that collects and analyzes non-numerical data (such as interviews, focus groups, and observations) to understand concepts, experiences, or phenomena in depth.

A research approach that combines both quantitative (numerical) and qualitative (non-numerical) data collection and analysis methods within a single study or program of inquiry.

A study design that looks backward in time, analyzing data that has already been collected or events that have already occurred.

A study design that follows participants forward in time from the present to observe outcomes as they occur.

A study where the researcher observes and measures outcomes without manipulating any variables or assigning treatments to participants.

A study in which the researcher actively manipulates one or more variables (e.g., assigns a treatment) to observe the effect on outcomes.

A structured approach for formulating a clinical research question by defining: Population, Intervention, Comparison, and Outcome.

A set of predefined characteristics that participants must have to be eligible for enrollment in a study.

A set of predefined characteristics that disqualify potential participants from enrollment in a study.

The number of participants or observations included in a study. An adequate sample size is essential for detecting true effects and ensuring statistical power.

The proportion of a population found to have a specific condition or disease at a particular point in time or over a specified period.

The probability of obtaining results at least as extreme as the observed results, assuming that the null hypothesis is true. A p-value below the significance threshold (usually 0.05) suggests the results are unlikely due to chance alone.

A range of values, derived from sample data, that is likely to contain the true population parameter with a specified level of confidence (commonly 95%).

A measure of association between an exposure and an outcome, representing the odds that an outcome will occur given a particular exposure, compared to the odds of the outcome occurring without that exposure.

The ratio of the probability of an event occurring in an exposed group versus a non-exposed group. Used in prospective studies to measure the strength of association.

The arithmetic average of a set of values, calculated by summing all values and dividing by the number of observations. It is sensitive to outliers.

The middle value in a sorted dataset. When data is skewed or contains outliers, the median is often a better measure of central tendency than the mean.

The value that appears most frequently in a dataset. A dataset can have no mode, one mode (unimodal), or multiple modes (bimodal, multimodal).

A measure of the amount of variation or dispersion in a set of values. A low standard deviation indicates values are close to the mean; a high one indicates they are spread out.

A statistical test used to determine whether there is a significant association between two categorical variables by comparing observed frequencies to expected frequencies.

A statistical test used to compare the means of two groups and determine if they are significantly different from each other.

A statistical method for comparing means across three or more groups to determine if at least one group mean is significantly different from the others.

A statistical method for modeling the relationship between a dependent variable and one or more independent variables. Linear regression predicts continuous outcomes; logistic regression predicts binary outcomes.

A statistical measure that describes the strength and direction of a linear relationship between two variables. Values range from -1 (perfect negative) to +1 (perfect positive).

A determination that the observed result is unlikely to have occurred by chance alone, typically when the p-value is below a pre-specified threshold (usually 0.05).

A calculation performed before a study to determine the minimum sample size needed to detect a clinically meaningful effect with a given level of confidence. Statistical power is the probability of correctly rejecting a false null hypothesis.

A false positive: incorrectly rejecting a true null hypothesis, concluding that an effect exists when it does not. The probability of a Type I error is denoted by alpha (usually set at 0.05).

A false negative: failing to reject a false null hypothesis, concluding that no effect exists when one actually does. The probability of a Type II error is denoted by beta.

The ability of a test to correctly identify individuals who have the condition (true positive rate). A highly sensitive test rarely misses true cases.

The ability of a test to correctly identify individuals who do not have the condition (true negative rate). A highly specific test rarely produces false positives.

A measure of how far a set of numbers are spread out from their average value. It is the square of the standard deviation.

A committee that reviews and approves research involving human subjects to ensure the study is ethical and that participants' rights and welfare are protected.

An independent body responsible for reviewing research proposals to ensure they meet ethical standards and protect participants' rights, dignity, and safety.

A set of ethical principles established by the World Medical Association for medical research involving human subjects, widely regarded as the cornerstone of research ethics.

The Health Insurance Portability and Accountability Act — a US federal law that sets standards for protecting the privacy and security of patients' health information in research and clinical settings.

An international ethical and scientific quality standard for designing, conducting, recording, and reporting clinical trials involving human subjects. Compliance ensures participant safety and data integrity.

A situation in which financial, professional, or personal considerations may compromise, or appear to compromise, a researcher's objectivity or judgment.

A form of research misconduct involving the invention or falsification of data, results, or records that were never actually collected or observed.

The act of using someone else's ideas, words, data, or other creative work without proper acknowledgment, presenting them as one's own original work.

Credit given to individuals who have made substantial contributions to the conception, design, execution, analysis, or interpretation of a research study and the drafting of the manuscript. ICMJE criteria define authorship requirements.

The written document submitted to a journal for publication, containing the full account of a research study including introduction, methods, results, and discussion.

A concise summary of a research paper, typically 150-350 words, covering the study's background, objectives, methods, results, and conclusions.

The process by which a scholarly manuscript is evaluated by independent experts (peers) in the same field before publication, to ensure quality, validity, and significance.

A metric that reflects the average number of citations received per paper published in a journal over a two-year period. Often used as a proxy for journal prestige, though increasingly criticized.

A publishing model where research articles are freely available online to anyone without subscription barriers. Authors typically pay an article processing charge (APC).

A fee charged by open access journals to authors (or their institutions/funders) to cover the costs of publication, peer review management, and dissemination.

A fraudulent or deceptive publication that prioritizes profit over scholarship, often charging APCs without providing legitimate peer review, editorial services, or proper indexing.

A free biomedical literature database maintained by the US National Library of Medicine, containing over 36 million citations from MEDLINE, life science journals, and online books.

The standard organizational structure for scientific papers: Introduction, Methods, Results, And Discussion. Most original research articles follow this format.

Standardized checklists and flow diagrams that guide researchers in reporting their studies completely and transparently, ensuring all essential information is included.

An international initiative that promotes transparent and accurate reporting of health research studies by maintaining a comprehensive library of reporting guidelines.

CAse REport guidelines — a reporting checklist for case reports to ensure completeness and transparency. Includes 13 items covering title, abstract, introduction, patient information, findings, treatment, outcomes, and discussion.

STrengthening the Reporting of OBservational studies in Epidemiology — a checklist of 22 items for reporting cohort, case-control, and cross-sectional studies.

CONsolidated Standards Of Reporting Trials — a guideline consisting of a checklist and flow diagram for reporting randomized controlled trials to improve their transparency and completeness.

Preferred Reporting Items for Systematic Reviews and Meta-Analyses — a checklist and flow diagram for reporting systematic reviews to ensure completeness and reproducibility.

Software tools (such as Zotero, Mendeley, or EndNote) that help researchers collect, organize, annotate, and cite bibliographic references in their manuscripts.