Sample range chart - control charts for variables, Operation Management

Sample Range Chart - Control Charts for Variables

Whilst the sample mean chart provides control over the process setting, it provides no protection from change (increase) in the standard deviation of the process output. The second control chart (shown here) provides this by means of control limits set out from the average sample range (¯R) , determined when the process was stable.

663_sample range chart 1.png

Again, the control limits are established as 1-in-40 warning and 1-in-1000 action limits. They are determined by multiplying the average sample range (¯R) by the appropriate D' coefficient from the table below.

Upper action limit = D'0.9999 ¯R

Upper warning limit = D'0.975 ¯R

Lower warning limit = D'0.025 ¯R

Lower action limit = D'0.001 ¯R

1434_sample range chart.png

In practice, the lower control limits are often omitted, the reasoning being that exceptionally low range values represent welcome consistency. However, such low-probability results are unlikely to be produced by a stable process, and may, in fact, be an indication that the measurements are incorrect.

Posted Date: 3/15/2013 6:05:46 AM | Location : United States







Related Discussions:- Sample range chart - control charts for variables, Assignment Help, Ask Question on Sample range chart - control charts for variables, Get Answer, Expert's Help, Sample range chart - control charts for variables Discussions

Write discussion on Sample range chart - control charts for variables
Your posts are moderated
Related Questions
Do results from the survey illustrate typical complaints about teams and specifically about team incentive rewards?

What is Divine Command theory? Given the power gap between God and humanity how do we make the moral demands work? How do we make Divine command theory work?

Types of Process Technologies - Assembly lines It was developed in the automobiles industry in U .S. A. Her two or more components are combined to manufacture a finished produ

Specifications for a part for a DVD player state that the part should weigh between 24.4 and 25.4 ounces. The process that produces the parts has a mean of 24.9 ounces and a standa

Six Operators are to be assigned to five jobs with the cost of assignment in Rs. given 10 marks in the matrix below. Determine the optimal assignment. Which operator will have no a

Risks identified in the project charter include events that if they occur will have either a positive or a negative effect on a project's objectives.


The annual demand for a product is 15,600 units. The weekly demand is 300 units with a standard deviation of 90 units. The cost to place an order is $31.20, and the time from order

What was Harley Davidson's current market price per share in 2007?

Steps in Layout Planning and Design For a given product at a stated volume of production a process most appropriate must be determined. The process that is determined like any