Carol Ptak, CFPIM, CIRM, DDPP, DDLP, ASTP is a Co-Founder and Partner at the Demand Driven Institute. Ms. Ptak is a past president of APICS and has authored and co-authored several books on MRP, ERP, Lean, and Theory of Constraints. Chad Smith, DDPP, DDLP, ASTP, is a Co-Founder and Partner at the Demand Driven Institute. Mr. Smith has coauthored and contributed to several books on MRP, Theory of Constraints, and the Demand Driven methodology.