Random assignment vs sampling – UGC NET Question

Random assignment uses chance procedures to place participants into different experimental conditions so that groups are equivalent on both known and unknown characteristics at the outset. It strengthens internal validity by making it more likely that observed differences in outcomes are due to the treatment rather than pre-existing differences. This process is distinct from random sampling, which concerns how participants are chosen from the population. Therefore, the term that correctly completes the stem is random assignment.

Option A:
Sampling refers to selecting individuals from the population for inclusion in the study, which occurs before participants are divided into groups. It addresses external validity rather than internal group equivalence.

Option B:
Allocation is a general word for distributing participants among conditions and may or may not be done randomly; the stem emphasises assignment “by chance,” which points specifically to random assignment.

Option C:
Random assignment ensures that every participant has an equal probability of being in any group, reducing systematic bias and supporting causal inference. Because the stem describes this process in experimental research, assignment is the appropriate completion and this option is correct.

Option D:
Randomisation is a broader term for using chance procedures in research (and may include random assignment), but the specific term for placing participants into experimental/control groups is random assignment, which is what the stem targets.