Exam 19: Statistical Process Control

The defect rate for a product has historically been about 1.6%.What are the upper and lower control chart limits for a p-chart,if you wish to use a sample size of 100 and 3-sigma limits?

Examine the Statistical Process Control outputs below.Answer the following questions. a.What is the sample size? b.What is the number of samples? c.What is the mean of sample 8;what is the range of sample 10? d..Is this process in control? Explain--a simple Yes or No is insufficient. e.What additional steps should the quality assurance team take?

Which of the following statements about acceptance sampling is TRUE?

The causes of variation in statistical process control are:

A process is operating in such a manner that the mean of the process is exactly on the lower specification limit.What must be true about the two measures of capability for this process?

Up to three standard deviations above or below the centerline is the amount of variation that statistical process control allows for:

A normal distribution is generally described by its two parameters: the mean and the range.

The ________ is a quality control chart that indicates when changes occur in the central tendency of a production process.

In most acceptance sampling plans,when a lot is rejected,the entire lot is inspected and all defective items are replaced.When using this technique the AOQ:

The Central Limit Theorem states that when the sample size increases,the distribution of the sample means will approach the normal distribution.

Acceptance sampling's primary purpose is to:

A bank's manager has videotaped 20 different teller transactions to observe the number of mistakes being made.Ten transactions had no mistakes,five had one mistake and five had two mistakes.Compute proper control limits at the 90% confidence level.

An x-bar chart is used when we are sampling attributes.

The purpose of process control is to detect when natural causes of variation are present.

If a process has only natural variations,________ percent of the time the sample averages will fall inside the ±3-sigma control limits.

Statistical process control charts:

The ________ is the lowest level of quality that we are willing to accept.

The ________ -chart is the chief way to control attributes.

A retail store manager is trying to improve and control the rate at which cashiers sign customers up for store credit cards.The manager takes several samples of size 50.He finds that each sample of 50 contained 5 credit card signups on average.Find p-bar and 99.73% control limits.

A consultant has been brought in to a manufacturing plant to help apply Six Sigma principles.Her first task is to work on the production of rubber balls.The upper and lower spec limits are 21 and 19 cm,respectively.The consultant takes ten samples of size five and computes the sample standard deviation to be .7 cm and the sample mean to be 19.89 cm.Compute C_p and C_pk for the process.Give the consultant advice on what to do with the process based on your findings.