Feedback - advantages of statistical process control, Operation Management

Feedback - Advantages of Statistical Process Control 

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
Discuss personal traits: which factors contribute to our personal traits? Take any of MBTI or Big Five Model trait and discuss how it may appear. Is there any probability that this

"Project Management" Please respond to the following: •Determine the key characteristics that should be considered when selecting project management tools for a health care organiz

What do you understand by “line balancing”? What happens if balance doesn’t exist?

A(n) _____ is a neutral facilitator between employees and managers who assists in resolving workplace disputes

A manufacturing firm is considering two locations for a plant to produce a new product. The two locations have fixed and variable costs as follows: Site Fixed Cost (Annual) Variabl

What are companies that have low customer contact and are capital intensive; yet provide a service, called?

can you please give me a simple example of markov analysis

Compare and contrast the Quality Circle and High Involvement applications of employee involvement

Midwest packaging's ROE last year was only 3%, but its management has developed a new operating plan that calls for a debt-to-asset ratio of 60%, which will result in annual intere

Describe how an organization can use double-loop learning to improve performance.