Monday, March 11, 2002

 
Process 101. This is the first of a series of entries that will cover policies, processes and procedures. In this weblog I'm going to concentrate on processes and procedures, and cover policies in Postcards from the Revolution when I launch my series on the Tarrani-Zarate Information Technology Management Model. In that series I will also be reviewing Mike Sisco's IT Manager Development Series, which is a 10-book collection of professional guidance that covers every facet of IT management. This series and the model that Linda and I developed are closely aligned.

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:

  1. PDCA is preventative through the use of statistical process controls, while ETVX is inspection-based.
  2. 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.
  3. 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.
This of course begs the question, why not use PDCA? Among the reasons why ETVX is used include:A Twist. Linda and I add a wrinkle to the traditional ETVX model by adding controls and constraints. These two elements were heavily influenced by the IDEF0 functional process model.

Definitions. Before proceeding I want to provide definitions of terms that you'll see in all subsequent entries:

Examples. A starting point is the ETVX summary, which describes the basics of the model and includes our additions. I also have examples of how the ETVX process was employed in projects in which Linda, myself, or both of us developed solutions based on the model:End Note. I'll be expanding on the ETVX model in particular, and processes in general in future entries. I'll also be providing related information in Postcards from the Revolution, so be sure to check that weblog as well.




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