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

Quantitative technology in management, what are the challenges of quantita...

what are the challenges of quantitative technology in management

Explain what are your recommendation to resolve this lawsuit, Scenario: Com...

Scenario: Commerce Clause ABC Freightways maintained its principal place of business in Arkansas. However, they provided trucking services in all states west of the Mississippi

Work study, techniques & applicationa

techniques & applicationa

Explain three major issues from a business perspective, When you look at th...

When you look at the field of benefits as an Employer what do you find to be the three major issues from a business perspective? Now look at benefits as an Employee and identify th

The soccer world cup is promoted, The Soccer World Cup is promoted aggressi...

The Soccer World Cup is promoted aggressively to both companies and fans. This is an example of marketing a(n) a. Event b. Idea c. Service d. Plac

Factors determining production control, Factors Determining Production Cont...

Factors Determining Production Control 1. Nature of Production: In job oriented manufacturing products and operations designed for some particular order which may or may not b

Exam of Operation Management, I will have an exam which has 100 Questions. ...

I will have an exam which has 100 Questions. I will have just 24 hours to complete it. My question about that is if you can answer them within this time and handle the answers to m

Explain product life cycle, How does a product life cycle differ from a pro...

How does a product life cycle differ from a product life cycle?

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