Clinical significance is a measure of whether a research result "matters" in the real world. For example, consider a hypothetical research study to see whether a new experimental drug helps treat memory loss in Alzheimer's disease. First, patients are given a series of neuropsychological tests to assess their memory. Next, the patients are given six months' of treatment with the new drug. Finally, patients' memory is tested again. In this hypothetical example, suppose that the test scores of patients given the drug actually increase 2-3 points by the end of the experiment. This increase may be enough to publish as a research finding -- but this doesn't necessarily mean that there will be visible improvement in the patients' ability to perform the activities of daily living, such as remembering names or balancing a checkbook.

While research results are often assessed through "objective" neuropsychological tests which generate numerical scores, clinical significance is often assessed through "subjective" measures, such as the impressions of a doctor or caregiver about whether a patient has really benefited noticeably from the treatment.