Below are given two sets – research methods (Set-I) and data collection tools…

Concept

A research method is defined by the kind of evidence it must gather, and its data-collection tool is whatever instrument can supply exactly that kind of evidence. Four evidence needs recur: a controlled measurement of an induced effect, an assessment of a characteristic that already exists in the participants, a self-reported description obtained from a sample, and documentary testimony about events that are already over.

So the matching rule is: identify what each method is allowed to do to its variable (manipulate it, only observe it after the fact, merely describe it, or reconstruct it from the past), and the tool follows.

Application to this item

1. Experimental method — the researcher manipulates an independent variable under controlled conditions and must measure the resulting effect on an outcome that is comparable across groups and across repetitions. That demands an instrument with fixed administration procedures, fixed scoring and established norms, i.e. standardized tests (a = iii).

2. Ex post-facto method — the presumed cause has already occurred and cannot be manipulated, so the researcher starts from a characteristic the participants already possess (an aptitude, a trait, a background attribute) and reasons backwards. The instrument therefore has to measure that pre-existing attribute, i.e. typical characteristic tests (b = iv).

3. Descriptive survey method — the aim is to describe the present status of opinions, practices or conditions across a large sample, which means asking many respondents the same set of items in a self-reported form: a questionnaire (c = ii).

4. Historical method — the events under study are past and cannot be observed, manipulated or administered a test. The only admissible evidence is documentary and testimonial, so the researcher works by using primary and secondary sources (d = i).

Cross-check

Two of the four pairings are fixed by elimination and confirm the rest:

• Only one tool can reach events that are already over — documentary sources — so the historical method takes i, and no other method has to.

• Only one tool collects self-reported description from a large sample — the questionnaire — which is exactly what a descriptive survey needs.

• That leaves the two test instruments for the two remaining methods, separated by whether the variable is induced by the researcher (standardized measurement of the effect) or already present in the participant (characteristic/trait measurement).

Correct matching: a – iii, b – iv, c – ii, d – i.