Control charts for attributes - statistical process control, Operation Management

Assignment Help:

Control Charts for Attributes - Statistical Process Control

Attribute data assume only two values, such as pass/fail or good/bad: they are counted rather than measured. Many quality characteristics can only be monitored in this way, such as the soundness of a soldered connection or the absence of components on a printed circuit board. Before proceeding further, a distinction must be made between defectives and defects. The term defective refers to a non-conforming item of output. A defect is a non-conforming feature of a single item of output: such an item may have more than one defect. Control charts for attributes have several advantages:

  • Collection of attribute data does not require measurement equipment and the skills to use them
  • They can be used to monitor any process, since the process output can be judged as either conforming or non conforming
  • Different attributes may be recorded on a single chart.

 

On the other hand, they have the following disadvantages:

  • Sample sizes are generally larger than for variables charts. Ideally, the sample size should be chosen such that, on average, at least one defective/defect is found in the sample
  • Attribute data do not indicate degrees of defectiveness: a non conforming item may be slightly defective or greatly defective.

 

Several attributes control charts have been devised, but those most commonly used are those described below. Two charts that look for defective items are discussed - the p-chart that looks at the proportion of defectives when the sample size is variable, and the np- chart that looks for the proportion of defectives in a constant sample size. Another sort of chart - the c-chart - is also described. This looks for the number of defects on an item.


Related Discussions:- Control charts for attributes - statistical process control

What are strategies for creating an open environment, 1 Develop an ld score...

1 Develop an ld score for the current layout. What problems can you identify with the current layout? 2. Use trial and error to come up with a better layout that lowers the ld s

Explain method for a company to advertise, How does Facebook compare with T...

How does Facebook compare with Twitter in terms of a method for a company to advertise? Is the audience different for the two? Are the risks/rewards different?

How many cells must be used to represent each constraint, In excel how many...

In excel how many cells should be used to represent each constraint?

Explain in words your motivation to do a good job, Describe in words your m...

Describe in words your motivation to do a good job? Does your company recognize your value? Is your salary/wages indicative of your value?

Step for construction of string diagram, Step  for construction of string D...

Step  for construction of string Diagram To construct a diagram the  following  steps are required. 1. Step 1 produce a scale map  of the work  area identifying  all machi

How employer pay for employee benefits, 1. Why would the government not tax...

1. Why would the government not tax us for the Employee Benefits we receive? 2. As a percent of payroll, how much does your employer pay for Employee Benefits? 3. Explain the

Describe the basic idea underlying the contingency view, Explain the basic ...

Explain the basic idea underlying the contingency view

Explain what is the number of late -tardy jobs, A single machine work cente...

A single machine work center has five jobs assigned to it. They are labeled, in the order of their arrival in the shop, as jobs A, B, C, D and E. The work center may work on only o

How develop a decision making process, Because of the aggressive actions of...

Because of the aggressive actions of his brokerage firm, a stockbroker feels pressure to recommend to a client a stock he does not consider a good investment. Please develop a deci

Alternative process sequences - products , Alternative process sequences - ...

Alternative process sequences - products Even when the type of process flow has been established, there remains the task of determining the particular sequence of processes t

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd