Which statement best describes an experiment's internal validity?

An experiment's internal validity is specifically concerned with the causal relationship between the independent and dependent variables. It assesses whether the changes observed in the dependent variable can indeed be attributed directly to manipulation of the independent variable, rather than being influenced by extraneous variables or confounds. High internal validity means that researchers can confidently conclude that their experimental treatment led to the observed effects, thereby supporting a strong causal inference.

When internal validity is strong, it indicates that the experiment effectively isolated the independent variable as the cause of changes in the dependent variable, allowing researchers to assert that the results are a direct outcome of their intervention. This is crucial for experimentation since establishing cause-and-effect relationships is a primary goal of such research.