PLAN
Establish the objectives and processes necessary to deliver results in accordance with the expected output (the target or goals). By establishing output expectations, the completeness and accuracy of the spec is also a part of the targeted improvement. When possible start on a small scale to test possible effects.
DO
Implement the plan, execute the process, make the product. Collect data for charting and analysis in the following "CHECK" and "ACT" steps.
CHECK
Study the actual results (measured and collected in "DO" above) and compare against the expected results (targets or goals from the "PLAN") to ascertain any differences. Look for deviation in implementation from the plan and also look for the appropriateness and completeness of the plan to enable the execution, i.e., "Do". Charting data can make this much easier to see trends over several PDCA cycles and in order to convert the collected data into information. Information is what you need for the next step "ACT".
ACT
Request corrective actions on significant differences between actual and planned results. Analyze the differences to determine their root causes. Determine where to apply changes that will include improvement of the process or product. When a pass through these four steps does not result in the need to improve, the scope to which PDCA is applied may be refined to plan and improve with more detail in the next iteration of the cycle, or attention needs to be placed in a different stage of the process.
Note: Some modern trainers now also refer to the "A" as "Adjust". This helps trainees to understand that the 4th step is more about adjusting/correcting the difference between the current state and the planned state instead of thinking that the "A" is all about action and implementation (which actually happens in the second ("D") stage).
More specifically:
Stage 1: We listen to your needs and we ensure the final targets.
Stage 2: We analyze the issue and the surrounding environment, legal, technical, and social.
Stage 3: We suggest the best possible solutions that satisfy our targets.
Stage 4: We agree on the final project, the cost and the time plan.
Stage 5: We implement the project, informing our client in agreed time intervals.
Stage 6: We install the solution, training our client for it’s correct use.
Stage 7: We follow up the progress of the results.
Stage 8: We proceed with corrections, if and when they are needed for best outcome.
Stage 9: We confirm the implementation on all corrections and their results.