8/19/2020 Quiz: HW 1 – Exploratory Analysis of Denim Data
HW 1 – Exploratory Analysis of Denim Data
Started: Aug 19 at 10:59am
Quiz Instructions
Denim is a data set for a fictitious company that manufactures jeans. The company treats denim fabric to make it appear ¡°worn¡±. Although appearance of the fabric is important, the company is also concerned about the strength of the treated fabric. Assume you are part of a team that is responsible for collecting and interpreting the data shown in the JMP file Denim.jmp. In particular, your contribution to the team is to perform a preliminary investigation by conducting an exploratory analysis and report initial findings. To help you understand the meaning of ¡°exploratory analysis¡±, read the background info below and complete the activity that follows. It is important that you carefully read the provided information. Every experiment requires at least some fundamental understanding of how a system behaves before it can be measured and analyzed. After reading the background information you will be shown instructions on how to access the data set.
Background
¡°Stone washing¡± is a general term used to describe many different procedures to process denim and has been in use by jean manufacturers since the 1970s. For one approach to this method, new denim is tumbled in an industrial washer with Pumice stone. This method tends to relax the denim while also giving it a fashionable look since the stones wear through the top layers of denim and leave the white thread visible from the outside. However, textile manufactures soon realized that this method, on its own, caused many problems such as damaging equipment and the garments themselves, staining garments with stone dust, using high amounts of electricity, among other sustainability issues like creating havoc on the environment.
Then, in the 1980s manufacturers began using enzymes in combination with stone washing. This process, sometimes referred to as biostonewashing, uses enzymes to fade and blotch colors while stones are still used to wear the material. The added benefits to this method are 1) more material can be processed in equipment since fewer or no stones are now needed in the washing machines, 2) fewer stones usually means lower fabric strength loss and less consumption of energy, and 3) allows specific areas of jeans to be targeted with the enzymes to produce a controlled worn look. The downside of enzyme use is that they still need to be washed out of the denim (requiring more water consumption by manufactures) and then discarded without causing yet another environmental catastrophe. Caustic soda and alpha amalyze can be considered in this category.
Sand blasting has become a more modern approach by manufacturers. This approach can achieve a ¡°targeted¡± worn look, but is more controllable than stone washing or the use of enzymes since areas of jeans, like back pockets, front of thighs, etc., can be targeted more specifically without further wearing the immediate surrounding area. Stencils used in combination with sand blasting can also create high
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8/19/2020 Quiz: HW 1 – Exploratory Analysis of Denim Data
contrast areas between worn and not worn denim, producing a different fashionable look. Another benefit over older approaches is that there is no worry about indigo dye staining pockets, labels, etc. which is likely to happen when using enzymes to break down the dyes. Like the other approaches, sand blasting also comes with its problems. Workers not wearing the proper equipment can inhale the dust byproduct of sand blasting. Consistent exposure to this dust over a period as little as a year, can cause major irreversible damage to a person¡¯s lungs. Further, this dust is still yet another contaminate that manufacturers have to properly deal with if we are serious about protecting our environment.
Open JMP and go to Help > Sample Data Library > scroll down and double-click Denim.jmp to open the necessary data file.
Question 1 7 pts
Identify the proper variable type by referring to the icon shown next to each variable.
Lot Number
Method
Size of Load (lbs.)
Sand Blasted?
Thread Wear Measured
Thread Wear
Discontinuous
Categorical
Metric
Unidenti ed
Continuous
Ordinal
Starch Content (%)
Continuous
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8/19/2020 Quiz: HW 1 – Exploratory Analysis of Denim Data
Question 2 2 pts
Fill in the missing value: n = ______
98
Question 3 2 pts
Quickly check how may samples contain a starch level greater than 50%.
1. First, go to Rows > Row Selection > Select Where … to produce a new window.
2. Choose your variable of interest and Boolean operator, enter the necessary value,
click Add Condition and then OK.
3. Look in the lower right window of the JMP data table to see how many are
¡®Selected¡¯.
Number of samples with a starch level above 50% = ____ .
Next, use JMP¡¯s Distribution tool to create distributions of all seven variables.
Question 4 2 pts
Do there appear to be any missing observations?
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8/19/2020 Quiz: HW 1 – Exploratory Analysis of Denim Data
Question 5 2 pts
Which group (i.e., lot number) of tested denim samples contain fewer observations than the rest?
0
Question 6 2 pts
Select the rows corresponding to only these observations by clicking on that particular bar in the distribution plot. Choose all that correctly describe the samples corresponding to this particular selection observations.
We may assume these samples are not as stiff as the others since they have low starch content compared to the remaining samples
None received the alpha amalyze enzyme to fade the material¡¯s color
Only one of the samples from this group were exposed to a sand blasting treatment None received the stone washing method to wear the surface material
Yes No
Question 7 3 pts
One last question pertaining to this subset:
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8/19/2020 Quiz: HW 1 – Exploratory Analysis of Denim Data
Question 8 2 pts
Which enzyme treatment seems to do a better job of relaxing the denim material?
caustic soda pumice stone alpha amalyze sand blasting
Suppose someone made a mistake when initially defining the Thread Wear variable. Now it is your job to fix it by redefining the level ¡®Moderate¡¯. Complete the following to fix this mistake.
The samples appear to have come from a than usual wash load since their corresponding load sizes are each
[ Select ] the [ Select ] quantile.
Note: Be sure to choose the most descriptive of the available choices
[ Select ]
Question 9 2 pts
How can you tell that a formula was used to create the column for Thread Wear? Thread Wear is related to Thread Wear Measured, which is a continuous variable
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8/19/2020 Quiz: HW 1 – Exploratory Analysis of Denim Data
Question 10 2 pts
To fix the mistake, right-click on the column header for Thread Wear and select Formula. This should produce a new window.
What wear values currently define a ¡®Moderate¡¯ level of thread wear?
Values [ Select ] a value of 4 but
[ Select ]
a value of 9.
Let’s assume the original definition is wrong because values of 4 should be included as ‘Moderate’ while values of ‘9’ shouldn’t be included.
Correct this by redefining ‘Moderate’ thread wear to include a value of ¡®4¡¯ but NOT include a value of ¡®9¡¯.
Further, suppose a member of your team requests your help in identifying the following probabilities. Use what you have learned so far and be sure to base your results upon your correctly redefined levels of thread wear.
Note: Round all final probabilities to two decimal places.
The column is made up of ordinal values
The column is made up of non-numerical values
A ¡®+¡¯ symbol appears next to the variable name in the Column box depicted in JMP¡¯s data table window.
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8/19/2020
Quiz: HW 1 – Exploratory Analysis of Denim Data
Question 11
2 pts
Question 12
2 pts
Question 13
2 pts
As part of wrapping up this analysis, let¡¯s take a closer look at the distribution of Starch Content.
Question 14
2 pts
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______
______
_____
8/19/2020 Quiz: HW 1 – Exploratory Analysis of Denim Data
Question 15 2 pts
Assuming starch levels were normally distributed, the notation for defining this distribution would be:
N( , )
Note: Provide parameter values rounded to one decimal place
Continuing with this normality assumption, find the following probabilities to two decimal places.
The amount of starch in a sample doesn¡¯t appear to be normally distributed. Create a normal quantile plot to make a more informed judgement. Fill in the blanks to describe what you see.
[ Select ]
percentage
[ Select ] [ Select ]
[ Select ]
to the histogram, the quantile plot suggests starch normally distributed since
fall on the straight, diagonal line.
Question 16 2 pts
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8/19/2020 Quiz: HW 1 – Exploratory Analysis of Denim Data
Question 17 2 pts
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