The Architecture of the Quality Control Charts Module
The general technology of the Quality Control Charts module is described in the Technology of the Statistica Quality Control Charts Module (Technical Note). The following paragraphs describe additional details of the architecture of the program, that permits users to build complex, fully automated, and completely customized quality control systems.
The Chart "Object." All statistics (e.g., means, sigma, etc.) for the control charts are automatically maintained and updated in a separate chart object. The chart object itself contains no user interface, and is relatively small in size. Hence, it can be deployed on a network in a variety of ways, and multiple instances of the chart object (different quality control charts of many variables and/or attributes) can be maintained simultaneous on a server (or servers). All computations for maintaining and updating the chart are performed by the chart object. Because the computational cost of updating the chart statistics is separated from the computations necessary to prepare an actual rendering of the chart, many options and choices are available to adapt the Statistica Quality Control programs to large scale, distributed processing environments, for monitoring rapid data streams (and or very large data volumes, such as those that are common in the chip production industry, where often thousands of characteristics need to be monitored).
- The Quality Control user interface, preparing charts, monitoring quality
- The computations for producing the actual chart and related output tables and graphs is performed by the Quality Control module. This module communicates with the chart object via the COM interface. Thus, the computations for producing a chart on the screen are separated from the computations necessary to maintain the chart statistics.
- Alarms, responding to chart events
- The chart object will fire various chart-critical events when appropriate (see also
Quality Control Events). Specifically, the chart object will signal the beginning of an auto-update event (e.g., due to the arrival of new data), the end of the updating event (when the chart statistics have been completely updated), the occurrence of various out-of-control conditions (e.g., sample out of control, observation outside of specification limits, runs rule violation, etc.), and so on. Any client of the chart object can respond to these events, and generate a customized response. The quality control module is a client to the alarm notification of the chart object, and user interface is provided to set up various responses to chart-critical events (e.g., to prompt for assignment of a cause in response to an out-of-control condition). However, in addition, an outside event handler (event sink) can be "hooked up" to the quality control chart object, and in this event handler a fully customized programmatic response can be implemented, using the Statistica Visual Basic tools.
To summarize, the Statistica Quality Control Chart facilities consist of (1) the user interface (Quality Control module) for specifying quality control chart and for requesting specific results tables and charts, and (2) the chart object, which exists "independently" to (a) maintain and update all computed statistics necessary for the chart, and (b) to monitor the chart and fire various messages to clients to inform them of chart-critical events. Of course, to the single user or application on a single compute, the distinction between these two processes is not necessarily apparent, and it in no way complicates the usability of the program in that case.
See also, Technology of the Statistica Quality Control Charts Module (Technical Note).