UGC NET Questions (Paper – 1)

Randomisation is the process of assigning participants to experimental and control groups using random mechanisms, such as random number tables or computer-generated sequences. This practice helps ensure that groups are equivalent on both known and unknown variables at the start of the experiment. By reducing systematic differences between groups, randomisation strengthens internal validity and makes it more likely that observed effects are due to the treatment. Hence, the procedure described in the stem is correctly called randomisation.

Option A:
Stratification involves dividing a population into homogeneous subgroups and can be used before sampling or randomisation, but it does not by itself eliminate selection bias in group assignment. It is more related to sampling than to within-experiment group allocation, so it is not the best answer.

Option B:
Matching pairs participants on certain characteristics such as age or ability before assigning them to groups, which can improve equivalence on those specific variables, but it is not purely random. It cannot control for all unmeasured variables, so it differs from the chance-based process emphasised in the stem.

Option C:
Option C, randomisation, uses chance to distribute both measured and unmeasured characteristics across groups, reducing the risk that pre-existing differences, rather than the treatment, explain outcomes. This aligns exactly with the purpose stated in the question.

Option D:
Standardisation refers to keeping procedures, instructions and conditions uniform across participants to reduce procedural variation. While important for internal validity, it does not address selection bias in the same way randomisation does.

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.