Sample mean chart - control charts for variables, Operation Management

Assignment Help:

Sample Mean Chart - Control Charts for Variables

This figure depicts a typical means chart, on which sample means would be progressively plotted, left to right. Two sets of control limits have been drawn symmetrically about the process population mean (estimated as the grand mean of several samples). The inner pair, the upper and lower warning limits, are positioned ±1.96 standard errors (s) above and below the population mean. For a stable process, there is a 1 in 40 chance that a sample mean will exceed the upper warning limit, and likewise for the lower warning limit. The outer pair, the upper and lower action limits, are positioned ±3.09s above and below the population mean. Again, for a stable process, there is only a 1 in 1000 chance of a sample mean breaching the upper limit, and likewise for the lower limit. If we determine the ranges of several samples, we can compute the average sample range (¯R). Remembering that the standard error s = σ / √n, we can take advantage of the findings of a statistician, Hartley, who quantified the relationship: σ = ¯R/dn where dn is a coefficient which varies with sample size. Hartley's constants (dn), for sample sizes 2 to 6, are presented in this table.

2077_Sample Mean Chart - Control Charts for Variables.png

For convenience, the coefficients 1.96/dn √n and 3.09/dn √n have been calculated for a series of sample sizes. These values are presented as A' 0.025 and A' 0.001 in this table.

Sample size             A'0.025                A'0.001 

2                                  1.23                 1.94 

3                                  0.67                 1.05 

4                                  0.48                 0.75 

5                                  0.38                 0.59 

6                                   0.32                0.50

The final expressions are, therefore:

Warning limits = μ+A'0.025 ¯R

Action limits = μ+A'0.001 ¯R


Related Discussions:- Sample mean chart - control charts for variables

Explain what is the role of a cio in today''s global business, 1. What is t...

1. What is the role of a CIO in today's global business environment? 2. Dr. Carr presents a good argument in the "IT doesn't matter" reading. Present your view of Carr's central

Explain total compensation system, How might a company's business strategy ...

How might a company's business strategy affect the contribution (pay-for-performance) policies and techniques of its Total Compensation system?

Notate primary keys in each table with solid underlining, Review the inform...

Review the information currently housed in Huffman Trucking%u2019s database, in the Entities and Attributes for Fleet Truck Maintenance file on the virtual Organizations site. (Cus

Explain what types of quality management processes, 1. Compare and contrast...

1. Compare and contrast each of the five organizational structures from your reading (functional, divisional, matrix, team-based, and virtual network). 2. If you were to choose

Define contribute toward building a more ethical environment, How can you c...

How can you contribute toward building a more ethical environment?

Explain methods for the number of gallons of gasoline, Following are two we...

Following are two weekly forecasts made by two different methods for the number of gallons of gasoline, in thousands, demanded at a local gasoline station. Also shown are actual de

Describe what are best buy strategic objectives, What are strategic objecti...

What are strategic objectives? What is the purpose of strategic objectives? What makes an effective strategic objective? What are examples of strategic objectives for you organizat

Explain four ps of marketing, Explain Four 'P's of Marketing. Four 'P'...

Explain Four 'P's of Marketing. Four 'P's of Marketing : Marketing may be described as a human activity directed at satisfying wants and needs by exchange processes. A market

What potential problems in flexible retirement programs, What potential pro...

What potential problems and benefits are likely with early or flexible retirement programs?

Explain frequently use experience and intuition to make, If managers freque...

If managers frequently use experience and intuition to make complex, nonprogrammer decisions, how do they apply evidence-based management, which seems to suggest that managers shou

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