What is the Plan-Do-Check-Act (PDCA) Cycle?
Variations: plan-do-study-act (PDSA) cycle, Deming cycle, Shewhart cycle. Understand the evolution of these variations.
The Plan-do-check-act cycle (Figure 1) is a four-step model for carrying out change. Just as a circle has no end, the PDCA cycle should be repeated again and again for continuous improvement. The PDCA cycle is considered a project planning tool.
Figure 1: Plan-do-check-act cycle
When Should You Use the PDCA Cycle?
Use the PDCA cycle when:
- Starting a new improvement project
- Developing a new or improved design of a process, product, or service
- Defining a repetitive work process
- Planning data collection and analysis in order to verify and prioritize problems or root causes
- Implementing any change
- Working toward continuous improvement
The Plan-do-check-act Procedure
- Plan: Recognize an opportunity and plan a change.
- Do: Test the change. Carry out a small-scale study.
- Check: Review the test, analyze the results, and identify what you’ve learned.
- Act: Take action based on what you learned in the study step. If the change did not work, go through the cycle again with a different plan. If you were successful, incorporate what you learned from the test into wider changes. Use what you learned to plan new improvements, beginning the cycle again.
The Pearl River, NY School District, a 2001 recipient of the Malcolm Baldrige National Quality Award, used the PDCA cycle as a model for defining most of their work processes, from the boardroom to the classroom.
The PDCA model was the basic structure for the district’s:
- Overall strategic planning
- Needs analysis
- Curriculum design and delivery
- Staff goal-setting and evaluation
- Provision of student services and support services
- Classroom instruction
Figure 2 shows their "A+ Approach to Classroom Success." This is a continuous cycle of designing curriculum and delivering classroom instruction. Improvement is not a separate activity—it is built into the work process.
Figure 2: Plan-do-check-act example
The A+ Approach begins with a "plan" step, which the school district calls "analyze." In this step, students’ needs are analyzed by examining a range of data available in Pearl River’s electronic data "warehouse." The data reviewed includes everything from grades to performance on standardized tests. Data can be analyzed for individual students or stratified by grade, gender, or any other subgroup. Because PDCA does not specify how to analyze data, a separate data analysis process (Figure 3) is used here as well as in other processes throughout the organization.
Figure 3: Pearl River Analysis Process
The A+ Approach continues with two "do" steps:
- The "align" step asks what the national and state standards require and how they will be assessed. Teaching staff also plans curricula by looking at what is taught at earlier and later grade levels and in other disciplines to ensure a clear continuity of instruction throughout the student’s schooling. Teachers develop individual goals to improve their instruction where the "analyze" step showed any gaps.
- The "act" step is where instruction is provided, following the curriculum and teaching goals. Within set parameters, teachers vary the delivery of instruction based on each student’s learning rates and styles.
Formal and informal assessments take place continually, from daily teacher assessments to six-week progress reports to annual standardized tests. Teachers also can access comparative data on the electronic database to identify trends. High-need students are monitored by a special child study team.
Throughout the school year, if assessments show students are not learning as expected, mid-course corrections are made (such as re-instruction, changing teaching methods, and more direct teacher mentoring). Assessment data become input for the next step in the cycle.
In this example, the "act" step is "standardization." When goals are met, the curriculum design and teaching methods are considered standardized. Teachers share best practices in formal and informal settings. Results from this cycle become input for the "analyze" phase of the next A+ Approach cycle.
PDCA Cycle Webcasts
For more information, view "An Introduction to the PDCA Cycle," a three-part webcast series by Jack ReVelle:
- Part 1: This introduction walks through the PDCA cycle’s origins in the scientific method, as well as its connection to the Deming-Shewhart cycles.
- Part 2: This webcast compares and connects PDCA to other methodologies, including define, measure, analyze, improve, control (DMAIC), lean, and ISO 9001.
- Part 3: The final webcast provides an example application of PDCA and explores the benefits of using PDCA.
Adapted from The Quality Toolbox, Second Edition, ASQ Quality Press.