What is the aim of random assignment in experimental research?

The aim of random assignment in experimental research is to ensure that every participant has an equal chance of being placed in any group. This method is critical for enhancing the internal validity of an experiment, as it helps to evenly distribute participant characteristics—both known and unknown—across the different experimental groups.

By using random assignment, researchers can mitigate the effects of confounding variables, which are outside influences that could skew the results. Because participants are randomly assigned, any individual differences are likely to be balanced out, allowing for a clearer interpretation of the causal relationship between the independent variable (the treatment or condition being tested) and the dependent variable (the outcomes being measured). This procedure allows researchers to make more reliable conclusions that can be generalized to a larger population.

Other approaches, like ensuring all participants share the same characteristics or maximizing differences between groups, compromise the integrity of the research by introducing possible biases and reducing the generalizability of the findings. Reducing costs does not relate to random assignment's purpose; rather, designing an effective random assignment process can sometimes incur additional logistical considerations and costs.