Exam 21: Statistical Process Control

Diaper Delivery Wrap-M-Up,a Ft.Lauderdale diaper Service,has 10 delivery men who each deliver diapers to 50 customers every day.Wrap-M-Up decides to record the proportion of diapers delivered on time for a 10-day period and construct a p chart to see whether the proportion is too erratic.The data are shown below: ​ ​ -{Diaper Delivery Narrative} Find the numerical value of the lower control limit for the p chart.

Describe the three essential parts of a control chart.

Which of the following process results indicate that a statistical process is out of control?

When the control chart shows a change in the mean of the process distribution,the result is referred to as:

The mean of the sample means and the pooled standard deviation of 50 samples of size 10 taken from a production process under control are found to be 225 and 16,respectively.The upper control limit for the chart is:

The process capability index measures the capability of the process to produce units whose dimensions fall with in the specifications.

The letter p in p chart stands for ____________________.

In statistical process control,a Type I error occurs if we conclude that the process is in control when it actually isn't.

Fifty samples of size 1,000 were drawn from a manufacturing process and the number of defectives in each sample was counted.The mean sample proportion was .05.The centerline for the p chart is 50.

Assembly Line Random samples of 200 parts were taken on an assembly line every hour for the past 25 hours.The number of defective parts is shown in the accompanying table. ​ ​ -{Assembly Line Narrative} Calculate the centerline and control limits for the p chart.

If a p control chart finds six increasing or six decreasing sample proportions in a row,this could be an example of assignable cause variation called a(n)____________________.

When the control chart shows a slow and steady shift (up or down)in the process distribution mean,the result is referred to as:

A level shift is a change in the ____________________ of the process distribution.

____________________ variation is caused by a number of randomly occurring events that are part of the production process.

To determine whether the process distribution standard deviation has changed,we use a(n)____________________ chart or a(n)____________________ chart.

What do you look for to determine when a process is in a state of statistical control?

40 samples of size 2,500 were taken from a production process that is under control.The mean of the sample proportions of defectives was .05.The lower control limit for the 3-sigma p chart is .0369.

For an control chart,you test a series of sample means.For each series of samples,we want to determine whether there is sufficient evidence to infer that the process mean has changed (i.e.reject H₀: the process is under control).Under what situation would you reject the null hypothesis based on the control chart?

Chance variation in general cannot be eliminated without changing the process.

To ensure that a manufacturing process is under control,40 samples of size 900 were drawn,and the number of defectives in each sample was counted.The mean of the sample proportion was .025.Then,the lower and upper control limits for the p chart are .0094 and .0406,respectively.