PDCA (plan-do-check-act) is an iterative four-step problem solving process typically used in business process improvement. It is also known as the Deming cycle, Shewhart cycle, Deming wheel, or plan-do-study-act. It was proposed by W. Edwards Deming in the 1950's and suggests that business processes should be analyzed and measured to identify sources of variation that cause products to deviate from customer requirements. He recommended that business processes be placed in a continuous feedback loop so that managers can identify and change parts of the process that need improvements. Plan: Design or revise business process components to improve results. Do: Implement the plan and measure its performance. Check: Assess the measurements and report the results to decision makers. Act: Decide on changes needed to improve the process.