Scenario: Suppose you joined a start-up company to produce paper helicopters which are intended to be an educational toy. The name of the company is California Choppers. The company consists of 5 people (Peter, Meir, Jennifer, Sara, and Selina) who were responsible for the product development, and who are now responsible for production.

Each of the 5 production personnel works for an 8-hour shift with a production output of 20 helicopters. Each of them uses their own tools and measurement equipment, so they are concerned that the performance of helicopters produced on different shifts may vary.

Your role in the company is to provide expertise for quality assurance. As a first step, the team has asked you to institute an SPC process to understand performance variability of flight times when the helicopter is dropped from 5 feet.

The flight duration data was collected for one week (5 shifts) and is shown graphically as a Shewhart control chart. The data from shift 1 (samples 1 to 20) was used to set the control limits.

This data set appears to be under control, but upon close examination, it was found that there may be l process shifts from operator-to-operator. The data is provided on the next page.

Their team leader is convinced that they can control the production with a Shewhart control chart, but the rest of the team is not so sure. So they hired you as an SPC expert! Your first assignment is as follows:

1. Explain why a Shewhart control chart is limited in its ability to detect smaller process shifts. You should use the data from the first five shifts to illustrate the points.
2. Propose an alternate control chart approach, and explain why it’s an improvement.
3. Graph the data using the alternative approach, showing the control limits.

Test-taking advice: This need not be a long document (max of 2 pages), but you need to be careful to articulate your ideas. I’d propose you format with an introductory paragraph, and then for each idea on why the Shewhart chart is limited- state the conjecture, and then explain why. Similarly, for the alternative approach, state your conjecture, and explain why it’s an improvement.

	Shift 1		Shift 2		Shift 3		Shift 4		Shift 5
1	Peter	1.644	Meir	1.903	Jennifer	1.510	Sara	1.668	Selina	1.812
2	Peter	1.823	Meir	1.852	Jennifer	1.576	Sara	1.909	Selina	1.729
3	Peter	1.585	Meir	2.060	Jennifer	1.350	Sara	1.807	Selina	1.808
4	Peter	1.464	Meir	2.206	Jennifer	1.561	Sara	1.939	Selina	1.600
5	Peter	1.807	Meir	1.730	Jennifer	1.752	Sara	1.894	Selina	1.638
6	Peter	2.062	Meir	1.715	Jennifer	1.607	Sara	1.232	Selina	1.758
7	Peter	1.213	Meir	1.898	Jennifer	1.208	Sara	1.723	Selina	1.461
8	Peter	1.770	Meir	2.263	Jennifer	1.444	Sara	1.624	Selina	1.756
9	Peter	1.834	Meir	1.960	Jennifer	1.462	Sara	1.433	Selina	1.310
10	Peter	1.581	Meir	1.875	Jennifer	1.895	Sara	1.438	Selina	1.684
11	Peter	1.512	Meir	1.921	Jennifer	1.426	Sara	1.490	Selina	1.640
12	Peter	1.693	Meir	1.688	Jennifer	1.269	Sara	1.588	Selina	1.596
13	Peter	1.751	Meir	1.912	Jennifer	1.463	Sara	1.473	Selina	1.786
14	Peter	1.608	Meir	1.942	Jennifer	1.424	Sara	1.577	Selina	1.891
15	Peter	1.689	Meir	1.421	Jennifer	1.465	Sara	2.046	Selina	1.847
16	Peter	1.970	Meir	2.072	Jennifer	1.101	Sara	1.730	Selina	1.422
17	Peter	1.993	Meir	1.995	Jennifer	1.903	Sara	1.658	Selina	1.984
18	Peter	2.049	Meir	1.852	Jennifer	1.429	Sara	1.565	Selina	1.808
19	Peter	1.551	Meir	1.495	Jennifer	1.570	Sara	2.009	Selina	1.389
20	Peter	1.829	Meir	1.400	Jennifer	1.666	Sara	1.778	Selina	1.847