Randomiserade

Randomiserade is the Swedish term for randomised, describing a process in which units—such as participants, beds, or experimental plots—are assigned to different groups by chance. The purpose is to create comparable groups and reduce selection bias, allowing more reliable conclusions about the effect of an intervention.

In research, randomisation is central to randomised controlled trials and other experimental designs. By allocating participants at random, researchers aim to balance known and unknown prognostic factors across groups and to provide a valid basis for statistical comparison of outcomes.

Common methods include simple randomisation (such as using a random number generator), block randomisation to maintain balanced group sizes, and stratified randomisation to ensure balance on important characteristics. Adaptive or restricted randomisation may be used in some trials but requires careful design and reporting.

The credibility of randomisation relies on allocation concealment and, when possible, blinding. Allocation concealment prevents foreknowledge of assignments during enrollment, while blinding reduces bias in data collection and outcome assessment. Analyses typically follow an intention-to-treat principle to preserve the benefits of randomisation.

Historically, randomisation was developed in agricultural experiments and was popularized in medicine in the mid-20th century, notably in clinical trials of antibiotics. Today randomiserade designs are widely regarded as the gold standard for evaluating interventions, though they may be impractical or unethical in some settings and external validity must be considered.