Randomization

Randomization is used in clinical trials to randomly assign participants to one of two or more treatment groups, such as the experimental group or the control group. This method is used to reduce bias and to ensure that the groups are comparable at the start of the study. The goal of randomization is to distribute both known and unknown factors that could affect the outcomes evenly across all groups, thereby minimizing the impact of confounding variables.

In randomized controlled trials, which are considered the gold standard in clinical research, participants are randomly assigned to receive either the intervention being tested or a standard treatment/placebo. Random assignment to groups is done after the participants have been assessed for eligibility and have been recruited, but before the intervention to be studied begins. This random allocation helps ensure that any differences in the outcomes between the groups are likely due to the treatment itself, rather than other factors like age, gender, or disease status.

Randomization enhances the internal validity of a clinical trial by reducing selection bias, where participants might otherwise be deliberately placed into groups based on specific characteristics or preferences. It also helps achieve a more accurate and reliable comparison between the groups. Common methods of randomization include simple randomization, block randomization (ensures equal group sizes), and stratified randomization (ensures groups are balanced regarding selected baseline characteristics).