By far the most critical step in the problem-solving process is to verify that the solution will in fact eliminate the problem. In addition, it is often the most difficult step. The most common method to evaluate a problem solution is to wait for implementation of the solution, then see if the problem goes away. However, too much time may be lost before conclusive information is available. Verification, where ever possible, should come before implementation.
Several approaches to verification are available. In engineering, design verification and production validation testing provides significant information. In the short term, a bench/lab test can be used to verify. In some cases dynamometer testing can provide verification. Long term one can monitor fleet response. For manufacturing, verification is by in-plant indicators. SPC can verify the elimination of the problem. Sometimes scrap rate reports and conformance audits provide information. Sometimes a designed experiment is part of verification.