Statistical Quality Control
A venture capitalist has just given you several million dollars to develop your dream product! Explain in detail what this product is and why people would buy it. (Think Steve Jobs and the iPhone – did people really think we needed “smartphones” back in 2007?)
Now it has gone into production and the manager is asking you, as the statistical expert, to use statistical methods to ensure quality control.
- Describe your product, its use and societal value in at least one paragraph. Humor is encouraged.
- You will generate a random dataset of N samples of defective proportions by completing the following steps:
- You will start with a random number by combining the last 2 digits of the year in which you were born plus the day of the month in which you were born. For example, if you were born October 3, 1990, your number would be 90 + 3 = 93. (If your number exceeds 100, subtract 100 from the total.) Call this X and it will seed your random number generation.
- Choose a number of samples, N. N should be between 5 and 10.
- In Excel, type =RAND()*X in a cell. Repeat N times. This will generate the proportion of defective products (out of 100) for your N samples.
- Use Excel QM to create a p-chart for a sample size, 100, and the number of samples, N. Share your p-chart. See video in Live Binder.
- Share Lower Control Limit (LCL) and Upper Control Limit (UCL).
- Is the product in control? If not in control, what sample(s) was outside of the limits, i.e. below LCL or above UCL?
- First Response: Read a classmate’s response. If the process is not in control, choose one or two out-of-control samples and remove from the process. Re-run the data and share the LCL, UCL and new p-chart. State whether or not the process is now in control. If not, how many samples are still outside of the limits?
- If your classmate’s process is in control, what happens if you change the number of standard deviations, z, in the formula to a value to less than 3?
Second Response: Read a different classmate’s response. Consider and describe at least three factors that they might use to maintain product quality or to bring their product into control.