The data from the drive quality tests conducted at DataStor over the past 150 shifts are contained in the file DATASTOR. The Data Description section contains a description of this data file.
Using this data set and other information given in the case, help Bill Roberts and Tony Escalera solve the quality problem they are experiencing at DataStor. In particular, speculate as to the source of the problem based on your analysis of the data. The Case Questions will assist you in your analysis of the data. Use important details from your analysis to support your recommendation.
Questions:
1. Has DataStor Company had a quality problem (4 returned shipments in 20 days)? Can the problem with unaccepted shipments simply be caused by random variation? What evidence leads you to your conclusion? Attach supporting evidence from your data analysis. (Hint: you need to think about the following probabilities)
· If the DataStor DS1000 hard drive production process at DataStor Company is in control, what percentage of the drives produced would be considered in nonconformance by Four-D?
· If the DataStor DS1000 hard drive production process at DataStor Company is in control, how often would shipments be found unacceptable by Four-D?
· What is the probability of four rejected shipments in the past twenty days assuming that the process has been in control all this time?
2. Why were the defective products not detected before the shipments? How can the problem be fixed?
3. If the problem with unaccepted shipments is due to an increase in drive nonconformances at DataStor, when were the low quality products produced (e.g., weeks, shifts)? What evidence leads you to your conclusion? Attach supporting evidence from your data analysis.