Berkson's Paradox (Berkson's Bias)
Here's your citation in American Psychological Association (APA) format:
Berkson's Paradox (Berkson's Bias). (n.d.). In Alleydog.com's online glossary. Retrieved from: https://www.alleydog.com/glossary/definition-cit.php?term=Berkson%27s+Paradox+%28Berkson%27s+Bias%29