randomizavimas

Randomizavimas, or randomization, is a methodological principle in experimental design and statistics. It means assigning experimental units, such as participants or plots, to different groups solely by chance. The aim is to reduce selection bias and balance known and unknown confounding factors, thereby improving the reliability of causal conclusions.

In practice, randomizavimas is used in clinical trials, laboratory experiments, agricultural research, and A/B testing in software. Common approaches include simple randomization, block randomization to control group sizes, and stratified randomization to balance key characteristics across groups.

Core concepts include allocation concealment, which prevents foreknowledge of assignments, and blinding where feasible to reduce measurement bias. Sequences for randomization are generated by computers or random-number tables and kept hidden until group assignment.

Benefits include reduced bias, improved group comparability, and stronger causal inferences. Limitations include possible chance imbalances, the need for adequate sample sizes, and practical issues such as noncompliance and missing data. Randomizavimas complements other good study design choices and does not by itself guarantee perfect balance.

Its development and promotion are associated with the design of experiments by early 20th-century statisticians, notably Ronald A. Fisher, who advocated for randomization and randomized block designs.