The plan phase of the plan-do-check- act (PDCA) cycle is the mostcritical one, which is why the activity’s context must be grasped before anything is planned. Adding the understand phase to the traditional PDCA cycle —creating UPDCA— ensures explicit attention is paid to what is going to be planned. PDCA helps improve the things that went wrong, but UPDCA is a powerful problem- prevention tool that ensures things are done right the first time.