Abductive reasoning -- ANCOVA -- ANOVA -- BACI -- Brown, Robert -- Burbidge, E. Margaret -- Cavendish, Henry -- Case study research -- Casual networks -- Chi-square goodness of fit test -- Chi-square test of independence -- Cluster sampling -- Comparative research -- Completely randomized designs -- Copernicus, Nicolaus -- Correlation modeling -- Correlational research -- Correlations and causations -- Crossover repeated measures design -- Cross-sectional sampling -- Curie, Marie -- Darwin, Charles -- Deductive reasoning -- Descriptive research -- Descriptive statistics -- Distributions -- Einstein, Albert -- Experimental research -- Explanatory research -- Exploratory research -- External validity -- Faraday, Michael -- Feynman, Richard -- Field experiment -- Fractional factorial designs -- Full factorial design -- Geller, Margaret -- Hawking, Stephen -- Higgs, Peter -- Histograms -- Holistic study (ethnography) -- Hooke, Robert -- Hypothesis testing -- Hypothesis-based study -- Independent rariable manipulation -- Inductive reasoning -- Internal validity (causality) -- Interpretive methods -- Kepler, Johannes -- Kruskal-Wallis test -- Laboratory experiment -- Latin square designs -- Leakey, Mary -- Linear and nonlinear relationships -- Longitudinal sampling -- Mach, Ernst -- Mann-Whitney U test -- Meitner, Lise -- Mendel, Gregor -- Mill's methods of casual reasoning -- Multiple case study -- Multistage sampling -- Nested analysis of variance -- Nested designs -- Nonequivalent dependent variables design -- Non-probabilistic sampling -- Nonresponse error -- Objectivity -- One-tailed and two-tailed t-tests -- Oppenheimer, J. Robert -- Pierce, Charles Sanders -- Plackett-Burman design -- Positivist methods -- Posttest-only design -- Pretest-Posttest experimental research design -- Probabilistic sampling -- Proofs -- Prospective chohort design -- Quadrat sampling -- Qualitative research -- Quantitative research -- Random sampling error -- Randomization -- Randomized complete block designs -- Regression discontinuity design -- Regression modeling and analysis -- Regression point displacement -- Replication, manipulation, and randomization -- Retrospective cohort design -- Sample frame error -- Sampling design vs. experimental design -- Sampling design: randomness and interspersion -- Sampling framework -- Sampling vs. census -- Significance levels -- Solomon four-group design -- Split-plot type designs -- Stratified random sampling/randomized block design -- Student's t-test -- Switching replications design -- Systematic sampling -- Time-series designs -- Type I and type II errors -- Turing, Alan -- Wu, Chien-Shiung.