Random assignment equal chance – UGC NET Question

Random assignment is the process of allocating participants to experimental and control groups purely by chance, such as by using random numbers or drawing lots. It ensures that, on average, the groups are equivalent with respect to both known and unknown variables before the treatment is applied. This greatly strengthens internal validity by reducing selection bias. Because the stem highlights equal and independent chances of being placed in any group, random assignment is the correct term.

Option A:
Random assignment ensures that individual differences are distributed approximately evenly across groups, so observed post-treatment differences are more likely due to the intervention. It is a defining feature of true experimental designs. This role matches the stem’s description, confirming random assignment as the appropriate completion.

Option B:
Matching involves pairing participants who are similar on certain variables and then assigning them to different groups, which partially controls for those variables but does not guarantee equal independent chance of group placement for all participants. Thus, matching is not the correct answer.

Option C:
Blocking is used to control for the effects of one or more nuisance variables by forming homogeneous blocks and then randomly assigning treatments within each block, especially in agricultural or industrial experiments. While it involves randomisation, the stem’s focus on general equal and independent chances for all participants is more directly captured by random assignment.

Option D:
Clustering usually refers to grouping participants based on natural units such as classes or schools in sampling or design and does not necessarily imply random allocation of individuals to treatment conditions. As such, clustering is not the proper term for the procedure described.