Retrospective research is deemed acceptable as research, but is not viewed as highly as randomised controlled trials. It is however, of more use than simple case studies or clinical experience, both of which also contribute to the growing knowledge base. It may or may not reach the standards you require, but personally this study made me ask a lot of questions that have helped me both personally and professionally.

A Retrospective Assessment of Network Care Using a Survey of Self-Rated Health, Wellness and Quality of Life
Robert H Blanks, Ph.D., Tonya L. Schuster, Ph.D., Marnie Dobson, MA Journal for Vertebral Subluxation Research Volume 1, Number 4 , 1997, p.15-31

Rachael Talbot is based in Wilmslow, Cheshire, where she runs a busy Chiropractic Office - Naturally Empowered Wellness & Chiropractic. She lives locally with her husband and two cats, Einstein and Schrodinger.

She is also the creator of the UnMasking the Feminine Podcast, and interviews Inspiring Women who have a story to share.