The QM for Windows Quality Control module can compute most of the SPC control charts and limits introduced in this chapter. Once the module is selected, we select New and indicate which type of chart (p-chart, x-bar chart, or c-chart). Program 15.5A displays the different possible choices in QM for Windows. When the p-chart is selected for the ARCO example, the initialization window opens, as displayed in Program 15.5B. We enter a title and the number of samples (20 in this example) and then click OK. An input window opens, and we enter the 20 sample values (number of errors or defects in the sample) and specify the sample size (100). We click Solve, and the output window opens, as illustrated in Program 15.5C. The original input data and the sample size are displayed, as are the results. While this problem has been set to use the three standard deviation (sigma) limits, other values are possible. QM for Windows computes the average proportion $\left(\overline{p}\right),$ standard deviation, and upper and lower control limits. From this screen, we can select Window and select Control Chart to actually view the chart and look for patterns that might indicate that the process is out of control.