What is meant by internal validity in research?

Internal validity refers specifically to the extent to which a study can demonstrate that the independent variable actually caused a change in the dependent variable. This concept is crucial in research because it allows researchers to determine if the observed effects in an experiment can be attributed to the manipulation of the independent variable rather than to other potential confounding factors.

When a study has high internal validity, it provides strong evidence that any changes in the outcome are a direct result of the experimental conditions applied, ruling out alternative explanations. For instance, if researchers are assessing the effectiveness of a new social work intervention on client outcomes, demonstrating high internal validity would mean confidently asserting that the intervention itself, and not other variables (like client background or external influences), led to any observed improvements.

In contrast, other options focus on different research validity concepts. The accuracy of measurement tools pertains more to measurement validity rather than causation. Generalizability relates to external validity, which assesses the applicability of findings to wider populations or settings. Consistency across multiple measurements refers to reliability, which evaluates whether a study's results can be replicated consistently under similar conditions. Understanding these distinctions is vital for effective research design and interpretation in social work and other fields.