Monday, March 11, 2002
The tie-in between policies and our model is at the business imperatives/business requirements layer.
Our Approach. Linda and I both use a process model that is called Entry-Task-Validation-Exit (ETVX) model. This model is similar to the Plan-Do-Check-Act (PDCA) process model that is an integral part of total quality management (TQM).
The similarities between the two models include: a structured approach that ensures correct input into a process, documented tasks (procedures), validation checkpoints and defined action. In the case of the ETVX process the sequence is linear and it's designed to take a process trigger or input, perform a series of tasks to produce something or transform the input, check the finished product against quality criteria and exit criteria. If all of the quality and exit criteria are satisfied the process ends (until the next triggering event or arrival of entry criteria), and if not, the discrepancy is corrected in the task phase. It then goes back through the validation phase, and either exits or is reworked until all quality and exit requirements have been met.
The PDCA model differs in subtle, but important ways. The plan and do phases are nearly identical to the ETVX entry and task phases. However, the PDCA check phase is designed for continuous improvement and measures whether or not quality is being achieved within upper and lower control limits defined in statistical process control charts. The most common charts are X-bar (mean) and R (range) charts. If there are indicators that a process is drifting out of statistical control, even if quality requirements are met, an action is initiated to investigate and rectify the root cause. One such indicator is more than three data points above or below the statistical mean in an X-Bar chart.
From the comparison there are key differences between the two models despite surface similarities:
- PDCA is preventative through the use of statistical process controls, while ETVX is inspection-based.
- PDCA is cyclic and designed to support continuous improvement by constantly measuring and comparing, while ETVX is sequential and only loops back into the task phase for rework.
- PDCA has early warning indicators built in, using trends to spot processes that are drifting out of control that can be remedied before quality is compromised. ETVX depends on the validation phase to spot out of conformance processes and has no mechanism other than rework to deal with quality problems.
- PDCA requires a strong commitment to implement and manage. It looks relatively simple on the surface, but the training, discipline and organizational commitment to make it work are high hurdles.
- Some processes are difficult to manage within the PDCA model, or PDCA would be overkill. It comes down to a business case to determine if the cost of non-quality outweighs the cost of quality. Approach it as an exercise in cost/benefit analysis to see which model makes more sense. Do bear in mind that PDCA imposes training costs, and also requires a change in most organizational cultures.
Definitions. Before proceeding I want to provide definitions of terms that you'll see in all subsequent entries:
- Process controls: limits that have been purposely placed on the process to prevent undesirable outcomes. Examples include:
- Audits and integrity checking.
- Error detection and correction processes.
- Process Constraints: Limitations imposed on a process are called constraints. Examples include technical capabilities, available time frames, resources, transmission speeds, etc.
The key difference between a control and a constraint is that a control is designed into the process to produce or effect a desirable outcome, while a constraint is a limitation to the process (or environment) that may impact on the effectiveness and/or efficiency of the process.
- Quality Gate: A checkpoint for verification and/or validation. tasks or procedures cannot proceed until the checkpoint has been successfully passed. If a quality gate fails the remedy is rework or other corrective measures.
- Contact Center Entry Criteria, developed by Linda for a project that required a problem management process. The criteria in this document is a subset of the entry criteria for production support, but there is sufficient detail to illustrate what constitutes the entry criteria phase of the ETVX model.
- Project Plan. This example is from the same problem management process project, and shows how ETVX can be applied to project planning. As a side note, this plan also follows the phases in the Rational Unified Process, which shows how ETVX can be used in conjunction with life cycle models.
- Change control process based on the ETVX model. This document shows an entire process aligned to the model.
- Change implementation plan, used in conjunction with the change control process. Note how the implementation plan is also structured using the ETVX model.
- Validation process, that not only uses the ETVX model, but also employs controls and constraints.
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