Question

1. The purpose of process control is to detect when natural causes of variation are present. TRUE or FALSE

2. A process range chart illustrates the amount of dispersion within the samples. TRUE or FALSE

3. Jars of pickles are sampled and weighed. Sample measures are plotted on control charts. The ideal weight should be precisely 11 oz. Which type of chart(s) would you recommend? Select one:

A. p-chart

B. c-chart

C. both a p-chart and a c-chart

D. an x-bar chart, but not an R-chart

E. both an x-bar chart and an R-chart

Answer 1

Answer 1. False

Explanation: The purpose of process control is to detect Assignable Cause of variation and not the chance or natural causes of Variations. Assignable cause are identifiable, specific cause of variation in a given process or measurement. A cause of variation that is not random and does not occur by chance is “assignable”.

Answer 2. True

Explanation: Process Range Charts are used to monitor the process variability or dispersion within the sample thereby detecting shifts int the process.

Answer 3. E. both an x-bar chart and an R-chart

Explanation: Mean charts (x-bar chart) and range charts (R-chart) complement one another, in a way that the mean chart detect the shifts in process average and the R-Chart detects the shifts in process dispersion. So, both should be plotted to check for average change and to detect the shift in the process.