Nyke- The Final Project
Yvonne Pearce
Thomas Edison State College
Principles of Statistics (2014Feb STA-201)
April 20, 2014

Thesis
People are the same. We all have similar body characteristics. We all generally have two eyes, two hands and two feet. Most of us also wear shoes. But producing shoes of varying sizes is expensive and time consuming. Nyke is proposing a plan to cut the cost of their production of shoes by only making one universal size shoe for their customer base. We will look at a sample of data obtained by this company and determine if this is statistically the best plan moving forward for this company.
Data Observations
A statistical study is only as good as its raw data. Nyke has provided a sample of thirty five of their customer base shoe sizes, heights and genders. This is a really small random sample based on the gross production of shoes already being produced by Nyke, however, we can make some recommendations based on these numbers. We will assume these numbers are correct, and the process of picking these data points were random.
Statistical Testing
There are many tests we can run on this sample of data to determine if it is viable. First we need to turn this data into numbers that we can use in our equations to calculate our values. So we need to convert the numbers into the mean, median, mode, range of values, x, x2 and the standard deviation of the data. Second, we will use the data to construct several graphs, such as a boxplot, histogram, stem and leaf plot and a scatter plot to determine if or how the data is skewed and if there are any outliers. If we identify any outliers we will determine whether these are errors. Third we will use a t-test, Chi squares and binomial approximation to construct a hypothesis about the data. Fourth, we will construct a linear regression and look for correlation. The analyzed data from these test should give us an idea of whether this plan of a universal shoe size will be right for the Nyke company.
Converting data into usable numbers First I put the data into an excel spreadsheet for ease of use. Then I broke up the data into the following categories: All shoe sizes, all heights, Women only shoe sizes, Women only heights, Men only shoe sizes, and Men only heights. Now we can calculate the mean, median, and mode of each of the different categories. We also can calculate the range, the standard deviation, the deviation from the mean, and the squared deviation from the mean. This will allow us to plug in these calculated numbers into various equations. One of the equations I was able to use now was the IQR range, which allows me to see how the data is skewed, and also gives me the upper and lower limits. These limits allow me to see if there are any potential outliers. This data only had one potential outlier; one data point of a women’s shoe size 10. Everything else fell between the limits. Shoe size- Whole Group | | Sample Mean | 9.14285 | Median | 9 | Mode | 7 | Range | 9 | Sample Stdev | 2.58266685 | Number of observations | 35 | Shoe size- Women Only | | Sample Mean | 7.11111 | Median | 7 | Mode | 6.5, 7, 7.5 | Range | 4 | Sample Stdev | 1.13183 | Number of observations | 18 |
Figure 1 Shoe size- Men Only | | Sample Mean | 11.29411 | Median | 10.5 | Mode | 11, 12 | Range | 6.5 | Sample Stdev | 1.803285404 | Number of observations | 17 |
Figure 1 (continued) 5 Number Summary | | | | | | | | | | Data Points | Min # | Q1 | Q2 | Q3 | Max | IQR | LL | UL | Outliers? | Shoe Size-All | 5 | 7 | 9 | 11 | 14 | 4 | 1 | 17 | No | Height- All | 60 | 66 | 70 | 72 | 77 | 6 | 57 | 81 | No | Shoe Size- Women Only | 5 | 6.5 | 7 | 7.5 | 10 | 1 | 5 | 9 | Yes,- 10 | Height- Women Only | 60 | 63.5 | 66.5 | 70 | 72 | 6.5 | 53.75 | 79.75 | No | Shoe Size- Men Only | 7 | 10.25 | 11 | 12.5 | 14 | 2.25 | 6.875 | 15.875 | No | Height- Men Only | 64 | 69 | 72 | 73 | 77 | 4 | 63 | 79 | No |
Figure 2
Graphing the data We now have a set of numbers associated with our data. We can use those along with our data points to graph. We have several graphs we can construct to help us understand our numbers better. I am going to make a box plot, histogram, stem plot and a scatter plot graphs. All four of these graphs will help point out the potential outliers, as well as give us an approximate shape of the distribution of the data. The graphs of “all shoes” and “women only shoes” were both skewed slightly to the left. The graphs of “all heights” and “men only heights” were both skewed slightly to the right. The “women height” and “men shoes only” were both bell shaped.

Figure 3

Figure 4

Figure 5
Relative frequency Next I took the data to see how frequently the shoe sizes for all the data occurred. The data shows a cluster for female shoes around a mode of size 7, and a cluster for male shoes around a mode of shoe size 11.5.
Conclusion
The data provided does not support the manufacture of just one shoe size. There is no common shoe size that would provide for a sizeable portion of both male and female customers. However, there is sufficient data to show that the manufacture of one shoe size for fermales, and one shoe size for males could reduce production costs with the least effect on profitability. The female shoe fit loosely as size 7 such that it could be worn by females sized at 6.5 and 7.5, would meet the needs of approximately 66% of the female population based on the sample data. The male shoe fit loosely at a size 11.5 such that it could be worn by males sized at 11 and 12, would meet the needs of approximately 41% of the male population. This being said, the total needs of 54% of the customer base can be met, while reducing the number of shoe sizes manufactured by 87.5% (from 16 sizes down to 2 sizes). This number is different if there are currently other shoe sizes manufactured not listed in the provided data.