To ensure that your results are valid, consider the following guidelines when you collect data, perform the analysis, and interpret your results.
If your data are the exact time and date of each event or elapsed time between events, use T Chart.
If the number of opportunities per day is not relatively constant, the chart may provide misleading results.
Because control charts detect changes over time, the order of the data is important. You should enter the data in the order it was collected, with the oldest data at the top of the worksheet.