What is the principle of randomization in experimental design?

The principle of randomization in experimental design is pivotal for ensuring the validity and reliability of the results. When participants are assigned to groups randomly, it helps eliminate selection bias, which could skew the results of the experiment. This random assignment means that every participant has an equal chance of being placed in any of the treatment or control groups, leading to more comparable groups.

By removing potential biases, randomization increases the likelihood that differences observed in outcomes are due to the treatment itself rather than pre-existing differences among participants. This enhances the internal validity of the study, allowing researchers to draw more accurate conclusions.

The other choices describe concepts that are not aligned with the principle of randomization. For instance, selecting participants based on specific characteristics introduces bias rather than eliminating it, replicating previous study results relates more to reliability and verification rather than random assignment, and limiting the number of participants to reduce costs does not address the fundamental purpose of randomization, which is to achieve unbiased group assignments.