Question

11. In general when plotting the proportion of defectives in each subgroup you data must be based on:

a) Binomial Distribution

b) Poisson Distribution

c) Normal Distribution

d) None of the above

12. The variation due to random shifts in factors that are always present in the process is defined in control chart terms as:

a) Random cause

b) Special causes

c) Common cause

d) In control cause

13. Which of the following statements is true?

a) Control Charts can only classified under three general types

b) Control charts can be used to monitor qualitative and quantitative variables

c) As a general rule it is always more efficient to use charts based on individual observations rather than averages

d) Generally, control charts are not very good at detecting changes in process variables

14. Tests for special causes detects a specific pattern in the data plotted on the chart. These tests are based on the following company rules:

a) WECO

b) WACO

c) MOTOROLA

d) DEMING

e) SHEWART

15. The following Control Chart should generally be used for Variable data and a subgroup size of 3

a) Xbar - R chart

b) I-MR chart

c) C-chart

d) np- Chart

Answer 1

11)

In general when plotting the proportion of defectives in each subgroup you data must be based on Normal Distribution.

Note: The normal distribution is used to approximate the distribution of the proportion of defective items
(?̂) in the P chart and the distribution of the number of defects per unit (? ̂) in the U chart. As the
subgroup size increases, the accuracy of this approximation improves.

12)

The variation due to random shifts in factors that are always present in the process is defined in control chart terms as Common cause.

13.

Control Charts can only classified under three general types.

Note: The control charts of variables can be classified based on the statistics of subgroup summary plotted on the chart.

X¯ chart

R Chart

S Chart

14)

Tests for special causes detects a specific pattern in the data plotted on the chart. These tests are based on the SHEWART company rules.

15)

The following Control Chart should generally be used for Variable data and a subgroup size of 3 X bar - R chart.

Note: An I-MR chart should have been used instead of an Xbar and R chart, since I-MR charts are for subgroup sizes of 1 and Xbar and R charts are for subgroup sizes greater than 1 (and typically less than 9 or 10).