Six Sigma Calculator

The Six Sigma calculator will compute the standard number of defects per one million opportunities (DPMO) and the process Yield (in percent), based on a given Sigma. You can also compute Sigma from a given DPMO, by setting the Inverse check box. Refer to Six Sigma Process for a discussion of the computational approach.

The Six Sigma Calculator tool will produce results consistent with most designated six sigma tables (e.g., see Harry and Schroeder, 2000; Pyzdek, 2001; Rath and Strong, 2000), and it is ideal to be used for a quick reference or training. The computations are based on a process shift of 1.5 * sigma, and the DPMO and the process Yield are computed based on a one-sided (one-tailed) criterion (see also Six Sigma Process). To perform detailed analyses of expected probabilities for the normal distribution, for a wide variety of non-normal distributions, use the general Probability Calculator facilities.

Send to Report

Select the Send to Report check box to send the computed values and parameters to a report. These values will be sent to a report when you click the Compute button, not when you change the parameters with the microscrolls. Therefore, you can edit the parameters using the microscrolls and review the results in the boxes in this dialog; then, when you are ready, click the Compute button to send the resulting values to a report. In order to send the graphs created when you select the Create graph check box to a report, select the graph window and then click the Add to report toolbar button.

Create graph

Select the Create graph check box if you want the Yield Density function and Yield graphs for the specified parameters to be placed in a compound graph (see also Six Sigma Process). The graph will be created when you click the Compute button, not when you change the parameters with the microscrolls. Therefore, you can edit the parameters using the microscrolls and review the results in the graph icons in this dialog; then, when you are ready, click the Compute button to create the desired graph. The compound graph is displayed in an individual window, regardless of the setting on the Options dialog box - Output Manager tab or the Analysis/graph Output Manager dialog box.

Inverse

Select the Inverse check box to compute Sigma based on a DPMO (defects per one million opportunities). See Six Sigma Process for additional details.

Sigma

If you enter the sigma value into this field, the Six Sigma calculator will compute the defects per one million opportunities in the DPMO edit field. If you enter the DPMO value, then the resulting Sigma value will automatically be updated in this field.

DPMO

If you enter the DPMO (defects per million opportunities) value into this field, the Six Sigma calculator will compute the Sigma value in the Sigma edit field. If you enter the Sigma value, then the resulting DPMO value will automatically be updated in this field.

Yield

The DPMO (defects per one million opportunities) field displays the number of defects that a process produces. The number of non-defects can be considered the yield of the process. This (output only) field reports the process yield, expressed as the percent of the (one-sided) area under the normal curve (given the 1.5 * sigma process shift) that falls below the respective specification limit. See also, Six Sigma Process for details.

Yield Density; Yield

These display fields show small graphs, depicting the normal curve and the cumulative normal curve associated with the current parameter values (Sigma or DPMO). See also, Six Sigma Process for a discussion of how the normal distribution is used in the Six Sigma Calculator.

Compute

Click the Compute button to compute the DPMO value from the current value of Sigma (if the Inverse check box is not set), or to compute Sigma from the current value of DPMO (if the Inverse check box is set). When the Send to Report check box is selected, clicking this button will also send these values to a report. When the Create graph check box is selected, clicking this button will create a compound graph containing plots of the Yield density and Yield for the specified values.