How is “validity” defined in research?

Validity in research is defined as the accuracy of a measurement in reflecting the concept it is intended to represent. This means that when a research tool (such as a survey, test, or observational checklist) claims to measure a specific concept—like intelligence, satisfaction, or health—it must do so effectively and accurately. If a measurement is valid, it means that it truly captures the essence of what it is measuring, rather than something else or a distorted version of the concept.

For example, if a test is designed to measure a student's understanding of mathematics, it should accurately assess their knowledge of mathematical concepts rather than their reading skills or general intelligence. Validation can take various forms, such as construct validity (how well the tool measures what it professes to measure), content validity (the extent to which the measurement covers the entire concept), and criterion-related validity (how well one measure correlates with another that is deemed to be authoritative).

In contrast, the other options do not address the concept of validity directly. The ease of data collection techniques pertains to practicality rather than accuracy; the inclusion of multiple methodologies relates to triangulation and robustness but not directly to validity; and the repeatability of research outcomes refers to reliability, which is a different aspect of measurements in research