When it comes to depression, clinical significance indicates behaviors and symptoms that are considered to be outside the range of normal, and are marked by distress and impairment of daily functioning.
Clinical significance is a different concept than statistical significance, or the mathematical determination of an event, symptom, behavior, etc. not occurring merely by chance.
While some statistically significant events may not be clinically relevant, clinically significant events may sometimes be statistically significant.
The criteria for a mood disorder and its clinically significant symptoms are set by the DSM-IV.
Example: Clinically significant sadness in a child would indicate that her symptoms have been present for at least two weeks, on all or most days, and that her sadness has affected her interactions with family and friends and significantly interfered with her ability to attend school or complete school work.
Clinically insignificant, or not clinically significant, sadness in a child might be temporary feelings of sadness lasting for three to four days with no other symptoms of childhood depression present.
Boris Birmaher, MD, David Brent, MD, et al.Practice Parameter for the Assessment and Treatment of Children and Adolescents With Depressive Disorders Journal of American Academy of Child and Adolescent Psychiatry. 46(11). November 2007. 1503-1526.
National Survey Confirms that Youth are Disproportionately Affected by Mental Disorders. National Institute on Mental Health. Accessed: March 24, 2011. http://www.nimh.nih.gov/science-news/2010/national-survey-confirms-that-youth-are-disproportionately-affected-by-mental-disorders.shtml