The minimum number of requests to produce an effective control chart of that process is twenty-five. In order to ensure that we reached this number, at least fifty requests were tracked through each of the seven processes. The start and end time for each workflow step in a given process was recorded along with the initials of the employee completing that step. The start and end times from the data collection sheets were input into an Excel chart which provided turnaround times for each process as well as processing time for each task. From this data, control charts were produced.
Control charts are a way of detecting and monitoring the variation in a process.
Charting the data in this format allows you to visually see each request with total turnaround time within set limits. Upper and lower control limits, which indicate how much variation is typical for the process, are calculated according to statistical formulas from the data collected. Points that fall outside the limits or into particular patterns indicate the presence of a special cause of variation, a cause that deserves investigation. The goal is to constantly monitor the process, and to reduce variation over time. In conjunction with producing control charts, we also produced Pareto charts for each of the seven processes.