UNIT 11

Question 1

The run chart vertical axis starts at 17 instead of zero. Select the most accurate statement below:

Answer 1

The graph is fine as is because it allows us to see how the points vary around the median and with respect to each other, including the overall trend. Including zero on the vertical axis would compress the line into a nearly straight line at the top of the graph

Question 2

What is the length of the longest run on the run chart?

Answer 2

4 (with margin: 0)
A run is a consecutive number of points that are either all above or all below the median line. In this chart longest run is 4, but there are two different runs of length 4: the points from 1980 to 1983 are all above the line, and the points from 1986 to 1989 are all below.

Question 3

The length of the longest run indicates that there are special causes

Answer 3

False

Question 4

How many runs are on the run chart?

Answer 4

7 (with margin: 0)
There are 7 runs on this chart: 1980-1983, 1984, 1985, 1986-1989, 1990, 1991-1992, 1993

Question 5

The number of runs indicate that there are special causes

Answer 5

False
For 14 data points, Table 4.2 in the Data Sanity paper shows us that if the data are random, we would expect 4 to 11 runs. Since the number of runs falls in this range we can conclude with a high degree of certainty that only common causes exist

Question 6

Rule 2 applies to the successive values starting with year

and ending with year

Be sure to enter the complete year, such as 1986, not 86 or ‘86

Answer 6

1986 to 1993

Question 7

Rule 3 applies to the successive values beginning with year

and ending with year

Answer 7

1980 to 1983

Note that three of the four values from 1980 to 1983 are in the upper 25% area. Only the 1981 value is below this area.

Question 8

Since Rules 2 and 3 apply to this chart, we can conclude that

Answer 8

The data seen in the chart results from both special and common cause variation

Question 9

What kind of statistical trend (if any) is shown in the X chart?

Answer 9

No trend

Question 10

Since the points that correspond with Rule 2 are above the central line and the points that correspond to Rule 3 are below the central line we can infer

Answer 10

It is likely that a change occurred somewhere between 1983 and 1984 that caused a drop in the percentage of high school seniors who smoke

Question 11

Based on the chart above, what can we infer about the change in the % of high school seniors who smoke?

Answer 11

The smoking rate shifted downward by about 2% between 1983 and 1984. There is no evidence of a change in the rate of teen smoking from 1984 through 1993.

Question 12

In the X chart shown above (the complete chart, not the split chart), what is the value of sigma? Round your answer to two decimal places. For instance, 5.423 would be 5.42 and 5.425 would be 5.43. Note that the average reference line on the X chart is at 19.271, whereas the upper control limit (UCL) is at 21.54.

Answer 12

0.76 (with margin: 0)
0.756 (with margin: 0)

Question 13

Suppose you have monthly data that begins:

If you are creating a moving range chart, what is the moving range for 6/1/93?

Answer 13

2.9 (with margin: 0)

Question 14

What is a likely consequence of management by outcomes–the practice of using incentives and disincentives to encourage people to achieve more desirable outcomes without any support or buy-in from management to improve the overall system in which people work?

Answer 14

Employees may fudge the numbers or game the system to meet the outcomes