What does the ‘R’ denote in experimental notation?

In experimental notation, the ‘R’ specifically denotes the random assignment of subjects to a group. This process is crucial in experimental research as it helps control for biases and ensures that each participant has an equal chance of being assigned to any of the treatment or control groups. By randomly assigning subjects, researchers can reduce the influence of confounding variables, allowing for a clearer interpretation of the effects of the independent variable on the dependent variable.

Random assignment enhances the internal validity of an experiment, as it helps establish a cause-and-effect relationship by ensuring that differences in outcomes can more confidently be attributed to the experimental manipulation rather than pre-existing differences between participants. This method is central to the integrity of an experimental design, as it supports the fairness and objectivity in the allocation of participants across different conditions.