Last updated: August 21, 2019
Topic: ArtDesign
Sample donated:

1.      List two common causes of variation that a NASCAR driver might experience during the process of driving in a race and why they are common causes.  (1 point)

Two common causes of variation that a NASCAR driver might experience include the length of the oval tracks and the number of turns for each track.  It is a part of the NASCAR system wherein the length of the oval tracks may vary from less than a mile to over two miles.  3 to 4 turns are also the variation with all of the turns going to the left.

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2.  List two special causes of variation that a NASCAR driver might experience during the process of driving in a race and why they are special causes.  (1 point)

Two special causes of variation that a NASCAR driver might experience include sudden breakdown of his car and a great miscalculation on the part of the driver that can lead to a collision.  These are special causes because these are unexpected events and considered out of bounds of the racing process.

3. What problems do we create for a process if we interpret common cause variation as special cause variation and take action on the process? (½ point)

When we interpret something as a special cause variation, we tend to focus on a single event and take action on that single event without taking into consideration other factors in the system.  When we misinterpret a common cause variation to be a special cause variation, we may find that we only contribute to the failing process because instead of improving the whole system given the common cause, we end up “tampering” with it.

4.  Explain a situation (and example) where special cause variation in a process might become common cause variation for the same process. (1 point)

One special cause variation could be the production of a defective machine, say a laptop.  In the middle of its use, the laptop malfunctions.  This becomes a common cause variation when the same thing happens for all the models of this particular laptop wherein we identify something wrong with the design or the production of this particular line of laptops.

5.  Choose the best answer:  (½ point)

Poka-yoke:

Replaces your quality system
Is used for source inspection
Is Japanese for “go to the work”
Can reduce human error
Is a replacement tool for Kaisen.
6.  List 3 mistake-proofing examples you can find around your home (note: they have to be different from examples in the website I listed in class).  (1.5 points)

·         A cassette tape can only be inserted in a given direction otherwise the slot will not close.

·         Microwave ovens automatically turn off when you open the door in the middle of heating.  They also turn back on and resume heating once you shut the door close.

·         Computer ports and slots are specific to each device that is to be inserted.  For example, the telephone port is a different size from the LAN port.  The monitor port is a different size from the printer port.  This avoids confusion when trying to assemble your PC.

7.  In order to deliver work faster or speed up lead time we need to focus on 2 key areas.  What are they?  (1 point)

These two key areas are cycle time reduction and invariance.

8. Choose the best answer: (½ point)

Visual order is an important component of:

a.       Gemba

b.      5 S

c.       Poka-Yoke

d.      VOC

e.       Heijunka

9.  Conceptually – what does a control chart tell you?  (½ point)

A control chart tells you whether or not a process is within statistical control limits by plotting collected data and analyzing the pattern/variation that is produced.

10. Why is it important to look at the range chart before looking at the Xbar or I chart when interpreting the data presented on control charts?  (½ point)

One should always take note first of the common causes of variation before looking at the special causes of variation.

11. There are 4 control charts shown below A thru D.  For each one, state whether the process is in or out of control.  If it is out of control, state why.  The dotted lines represent the UCL and LCL for each.  (½ point each)

A.    The process is out of control noting that the plotted points go beyond the upper and lower control limits.

B.     The process is out of control with eight points plotted below the center line.

C.     The process is out of control with a row of seven points plotted in a row upward.

D.    The process is out of control with several points plotted very closely to the upper and lower limits.