The quality assurance phase of monitoring results for technical compliance and cost control is an ongoing process of constant vigilance and continuous improvement. This step seeks to ensure that the product or service is being provided in accordance with the plan, a plan that includes technical, schedule, and cost goals. On this triangle, the customer is at the apex spinning off data about the validity of the work received. This information goes down the leg of the triangle to the right corner as data to be processed. The data go along the base of the triangle becoming an improved process.
Process improvements commence at the left corner and go back up to the apex for customer judgment.
Then the process starts over again. There are many approaches to monitoring and controlling processes. In fact, many companies consider SPC to be part of the integrated CIM approach, whereby SPC action steps are included in the MRP II scheduling algorithm. Most recently we've seen companies use the six-sigma variant of SPC to gain even further competitive advantage by approaching the very difficult goal of zero defect. ISO 9000 only states that you have a control system that you follow faithfully and have records to prove it.