Gerald J. Langley is a statistician, author, and consultant, and co-founder of Associates in Process Improvement (API), a consulting firm that specializes in the improvement of quality and productivity.

Ronald D. Moen is a statistician, consultant, and teacher to industry, government, and education. He is co-founder of API.

Kevin M. Nolan is a statistician, author, and consultant at API, where he focuses on developing methods and assisting organizations to accelerate their rate of improvement in quality and productivity.

Dr. Thomas W. Nolan is a statistician, author, and consultant, and¿co-founder of API.

Clifford L. Norman is a consultant with API whose work has emphasized the psychology of change.

Lloyd P. Provost is a statistician who advises to organizations as an API associate.