Experimental method

The experimental method tests explanations by deliberately varying conditions, controlling relevant factors, and observing outcomes. Its defining feature is intervention that can distinguish competing causal accounts.

Hypothesis: A proposed explanation or prediction that can be assessed against evidence. An experiment begins with a claim specific enough to test.
Independent variable: A variable deliberately changed or assigned to examine its effect on another variable. It identifies the intervention whose effect the experiment tests.
Randomized controlled trial: A study that randomly assigns participants to an intervention or comparison condition and measures outcomes. It applies controlled intervention to estimate treatment effects in people.
Observational study: A study that records exposures and outcomes without assigning an intervention. Unlike experiments, it does not deliberately allocate the condition under study.
Experimental design: The plan for assigning conditions, collecting measurements, and analyzing an experiment. Design turns the method’s logic into a concrete comparison.
Dependent variable: A measured outcome whose variation is studied in relation to other variables. It records the response to the experimental intervention.
Factorial experiment: An experiment that tests multiple factors and their combinations within one design. It can reveal whether interventions interact rather than act independently.
Correlational study: A study that measures whether variables vary together without establishing that one causes another. It can reveal associations but lacks experimental control over causes.
Control group: A group that does not receive the intervention being tested, providing a comparison for outcomes. It helps isolate effects attributable to the intervention.
Confounding: A distortion of an estimated relationship caused by another factor associated with both exposure and outcome. Confounders can make an intervention appear effective for the wrong reason.

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