Process Improvement Plan
March 19, 2012
Ray E. Mowery
Process Improvement Plan
In week one of this course, the students were asked by the instructor to select a process that the student performed on a daily basis. This student chose the task of driving to work. The student collected driving times for four weeks. This paper will cover the explanation of the control limits, including calculations and data used to determine them. The paper will discuss the effect of any seasonal factors as well as the confidence intervals and their usefulness based on the number of data points. The data for four weeks of driving to work is:
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Typical objectives of process control plans are to provide timely information on whether currently produced items are meeting design specifications and to detect shifts in the process that signal that future products may not meet specifications. Statistical process control (SPC) involves testing a random sample of output from a process to determine whether the process is producing items within a preselected range (Chase, Jacobs, & Aquilano, pg. 354, 2005).” The preselected range that would be acceptable for a drive time to work would be times that were ± 7.34 minutes from the average driving time of 30 minutes and fourteen seconds. So, any drive time that is between twenty two minutes and twenty six seconds and thirty seven minutes and forty eight seconds would be acceptable drive times to work for this student. “It is generally accepted that as variation is reduced, quality is improved (Chase, Jacobs, & Aquilano, pg. 348, 2005).” When a process is in control or capable, the mean and standard deviation of the process are operating such that the upper and lower control limits are acceptable relative to the upper and lower specification limits (Chase, Jacobs, & Aquilano, 2005).
A couple of factors that may affect the process design are traffic and weather. In Northeast Ohio, February and March can be extremely unpredictable as to what the weather has in store for it. It could be a balmy 50 degrees with clear blue skies, or severe winter weather with all the wonderful winter weather specialties, such as black ice, excessive amounts of snow and wind. If the student wakes up to an unexpected snowstorm, this could double or even cancel the drive to work. During the warmer months, there is no threat of dangerous driving conditions, so the student is able to maintain adequate speed limits to eliminate several minutes from the drive time. The amount of traffic and the number of traffic lights that the student may have to either sit at or drive through without stopping are variables that the student has no control over. During the four weeks that the data was collected, the student did notice that if the student was able to leave the house before 6:25 am, the traffic tended to be lighter then after that time,...