In quality management, a four-step process for quality improvement. In the first step , a plan to effect improvement is developed. In the second step , the plan is carried out, preferably on a small scale. In the third step , the effects of the plan are observed. In the last step , the results are studied to determine what was learned and what can be predicted. The plan-do-check-act cycle is sometimes referred to as the Shewhart cycle and as the Deming circle . Synonyms: Shewhart Cycle. Also see: Deming Circle