Question 1: To save money, the quality control engineer at a plant decided to use a sample of size n=2 on a line producing 500 parts per chart. (a) What could you tell him about the advisability of using such a small sample? (b)What effect will this approach have on the control charts and the information they will yield. (5 marks)
Question 2: (a) Why is it so important that sampling g schemes be carefully chosen? (b) Give an example of how an unwise selection of a sampling scheme can affect the resulting usefulness of the control charts made? (4 marks)
Question 3: Suppose you take a random sample of 40 from a lot of 1,000 items but later realise that you should have selected a sample of 70 items instead. How do you correct this error? Should you put the 40 items back and draw the required random sample of 70 from the original lot, or should you simply draw an additional random sample of 30 from the 960 remaining items?
(2 marks)
Question 4: The results of laboratory consolidation tests (sample of size 1) for four soil samples obtained from 4 different strata are given in table 1. These test results are used to compute the soil settlement that will occur if a certain load is placed on these strata. In building industry, high soil settlement means more movement in the building.
Use X-bar (with test options at raw 1, 5 and 8) and Moving rang charts to monitor consolidation data on these strata by answering the following questions.
- Interpret the charts for each site, comment on the Patterns or trends in each chart.
- Is there evidence that the soil settlement for these strata is uniform between the four sites? Explain your reasons.
- Which site would you recommend using? Explain your reasons.
- The manger was hoping to see the average soil settlement of 10.2 in all these strata. Continue you charting process similar to part (a) by using this value as your process mean. Interpret the new charts.
- Is the manager’s expectation of the soil settlement level a correct assumption? Explain your reasons.
- Which one of these strata would you recommend based on part d analysis? Explain your reasons.
- Write a100 words repot for the manager to communicate your finding and guide him to choose the best site.
| Site 1 | Site 2 | Site 3 | Site 4 |
| 9.7959 | 10.9076 | 9.4409 | 13.1946 |
| 8.7790 | 9.3148 | 7.3330 | 12.2903 |
| 11.6251 | 10.9922 | 7.5492 | 12.2046 |
| 10.6764 | 11.4413 | 7.9515 | 13.2692 |
| 10.4865 | 10.7417 | 7.7210 | 12.0333 |
| 11.6350 | 10.6445 | 8.8807 | 13.3472 |
| 8.3130 | 11.0823 | 8.9115 | 11.6671 |
| 9.2793 | 10.5391 | 9.5956 | 12.1243 |
| 9.2917 | 11.0755 | 8.9191 | 11.9862 |
| 10.5097 | 10.1638 | 8.1121 | 11.2154 |
| 10.2084 | 11.1507 | 10.3723 | 11.8289 |
| 9.4184 | 10.1381 | 8.5451 | 10.7120 |
| 10.5037 | 8.1387 | 8.6079 | 12.8071 |
| 9.5284 | 10.4141 | 9.4695 | 12.5941 |
| 9.5115 | 10.2263 | 9.1592 | 12.8422 |
| 9.2679 | 10.6389 | 11.3781 | 13.1562 |
| 10.4708 | 10.6315 | 8.6509 | 11.4001 |
| 10.7232 | 9.6346 | 10.0506 | 11.3515 |
| 11.0403 | 10.1104 | 9.6920 | 11.3908 |
| 10.0987 | 11.6428 | 7.2472 | 12.2071 |
| 7.5510 | 11.3604 | 10.1491 | 12.3324 |
| 9.9498 | 12.1617 | 8.5718 | 12.7403 |
| 10.0922 | 10.8213 | 8.2289 | 11.0279 |
| 9.6299 | 9.8491 | 9.9954 | 12.2233 |
| 9.9857 | 9.9320 | 8.2156 | 11.6305 |
Assignment 1 Rubric
|
Ratings | Pts | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Assessment Criteria 1 – Elucidate techniques and concepts of Statistical Quality Control. | 10.0 pts
High Distinction |
7.5 pts
Distinction |
6.5 pts
Credit |
5.5 pts
Pass |
0.0 pts
NN |
10.0 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Assessment Criteria 2 – Construct the appropriate Quality Control charts / Forecasting and
critically discuss the role of such charts / models in monitoring a process. |
10.0 pts
High Distinction |
7.5 pts
Distinction |
6.5 pts
Credit |
5.5 pts
Pass |
0.0 pts
NN |
10.0 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Assessment Criteria 3 – Assess the ability of a process to meet customer expectations.
Explain technical material, without unnecessary jargon, to lay persons. such as the public or line managers.
|
10.0 pts
High Distinction |
7.5 pts
Distinction |
6.5 pts
Credit |
5.5 pts
Pass |
0.0 pts
NN |
10.0 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Total points: 30 | 40.0 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Total Quality Management, task on Practical package utilisation and report writing on control charting.
|
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| Criteria | Ratings | Pts | ||
| This criterion is linked to a learning outcomes 1, 2
Question 1 |
|
8 pts | ||
| This criterion is linked to a learning outcomes 1, 2
Question 2 |
|
10 pts | ||
| This criterion is linked to a learning outcome 1
Question 3 |
|
8 pts | ||
| This criterion is linked to a learning outcomes 1, 2
Question 4 |
|
4 pts | ||
The following marking break will be applied To Explanation/ interpretation section of each question.
| Criteria | Not acceptable
(0) |
Needs Improvement
(25%-50%) |
Good
(75%) |
Outstanding
(100%) |
| Explanation/
Interpretation |
No clear conclusion/answer to the question
|
Needs improvement on the following,
– State conclusion – Adequate response to the question/ task – Restatement of argument/
|
Could improve the following
– Coherent statement of conclusion/s – Clear response to the question/ task – Clear restatement of argument/ findings
|
Information builds a strong and interesting rationale driving the investigation. Important concepts are detailed. |
