experiments

An experiment is a systematic procedure undertaken to test a hypothesis through controlled observation and manipulation of variables. Experiments aim to establish causal relationships rather than mere correlations, by isolating factors and repeating measurements under defined conditions.

A typical experimental design involves a hypothesis, independent and dependent variables, control conditions, random assignment or counterbalancing, replication, and predefined procedures for data collection and analysis. Randomization helps reduce bias; controls establish a baseline for comparison; replication increases reliability.

Common types include controlled experiments, in which the researcher manipulates the independent variable in a laboratory setting; field experiments, conducted in real-world environments; natural experiments, where researchers observe naturally occurring variation; and quasi-experiments, which lack full random assignment but still compare groups.

Ethical considerations include informed consent when human subjects are involved, risk minimization, data integrity, and transparency in reporting methods and results. Experimental studies are often preregistered and reported according to established guidelines to improve reproducibility.

Historically, experiments have been central to the scientific method. Early proponents such as Francis Bacon promoted empirical inquiry; Galileo and others used controlled observations to challenge prevailing theories. In modern science, experiments span disciplines from physics to psychology and medicine, and are complemented by observational studies and computational simulations.