What does randomization help to eliminate in experimental research?

Randomization is a fundamental technique used in experimental research to ensure that the participants in a study are assigned to different groups in a way that is free from bias. This process involves randomly assigning participants to experimental or control groups, which helps to create equivalent groups at the start of the experiment.

By doing so, randomization effectively eliminates systematic bias. Systematic bias occurs when participants in one group have inherent differences that could affect the outcome of the study, which could be due to factors such as age, gender, or prior experiences. When these biases are present, they can skew the results, making it difficult to determine whether the experimental treatment or intervention was truly effective.

In contrast, randomization ensures that any potential confounding variables are distributed evenly across all groups. This means that any differences observed in the outcome can be attributed more confidently to the experimental manipulation rather than pre-existing differences among participants.

While participant dropout, sample size discrepancies, and testing effects are important factors to consider in experimental research, they are not directly addressed by randomization. Randomization mainly focuses on establishing initial group equivalence, which is crucial for achieving valid and reliable results.