Feedback - advantages of statistical process control, Operation Management

Feedback - Advantages of Statistical Process ControlĀ 

SPC is a clear example of negative-feedback system control, providing management with timely information on the state of the process, allowing corrective action to be taken if required. Equally, SPC indicates when a process should be left to run, thereby saving on unnecessary adjustments to the process and, perhaps, avoiding non- conformance which could result from such adjustments. The following simple example may help to make the latter point clear. Consider a process with a target output value of 10.0 which, when running in a stable manner, has an inherent variability (see common cause variability, later) such that 50 per cent of the output is at the mean output value, 25 per cent measures 0.1 below, and the balance of 25 per cent measures 0.1 above the mean output value. Assume that the initial process setting is such that the mean output value matches the target value of 10.0. Twelve consecutive measurements might produce the following results (see table). Note that none of the measured values are outwith the expected range: with SPC, no adjustment of the process would be recommended.

53_Feedback - Advantages of Statistical Process Control.png

Now consider the same situation in the absence of SPC. The operator can adjust the process setting but cannot directly determine its mean value: he can only measure individual instances of the output, which, as we have seen, may differ from the mean as a result of the inherent variability of the process. Suppose, now, that the operator measures each output, calculates the deviation from the target value and adjusts the output by that amount. In the next table, the first output value (10.1) is above the target value (10.0) by 0.1. He adjusts the process setting to reduce the output value by this amount but, unknown to him, the process setting is now 9.9. As a result, the second output value is 9.8, not 9.9 (as it was in the previous table). The deviation is now 0.2 below target. The operator adjusts the process to increase the output by 0.2, taking the mean setting from 9.9 to 10.1, and so on.

1528_Feedback - Advantages of Statistical Process Control 1.png

Notice the effect: under SPC, as shown in the first table, six of the values would be at the target value and the others would range between 0.1 above to 0.1 below target. In the absence of SPC, as shown in the second table, only two of the values are on target and the others range from 0.1 above to 0.2 below target. The process adjustments have increased the variability of the output.

Posted Date: 3/15/2013 4:16:42 AM | Location : United States







Related Discussions:- Feedback - advantages of statistical process control, Assignment Help, Ask Question on Feedback - advantages of statistical process control, Get Answer, Expert's Help, Feedback - advantages of statistical process control Discussions

Write discussion on Feedback - advantages of statistical process control
Your posts are moderated
Related Questions
Someone Help Please! Select one of the following companies to study in depth over the next 4 weeks. BP Oil Kimberly-Clark Kroger Nucor Walgreens Wells Fargo Kaiser Permanente Ascen


What is the difference in strategy in developing an initial layout for a new facility as comparedn to the strategy in improving the layout of an existing facility?

Discuss how laws tie into business ethics. Support your ideas with research and specific examples of laws discussed in your text.

You discover an antique in your attic that you purchased at an estate sale 10 years ago for $400. You auction it in eBay and receive $8000 for your item. What is the annual rate of

A company's sales potential would be equal to market potential when which situations exists? a. Industry marketing expenditures approach infinity for a given marketing env

Assume that Z is made of two units of A and four units of B. A is made of three units of C and four of D. D is made of two units of E. Lead times for purchase or fabrication of ea

Define what mechanisms are related to the organization's SWOT in order to unfreeze, change, and refreeze (Lewin's theory of change) HR/business practices across the global organiza

Why is it important to continuously update the implementation and communication of a strategic plan? Who should be responsible for updating and communicating a strategic plan? Why?

What key technological features of SAP set it apart from conventional business accounting/planning/control software?