Statistics tab

By clicking the Session menu and then clicking Retrieval Settings, you can specify how the program should calculate statistics for the most recent data that is displayed during data entry. (In PDA mode, these options are not available.)

Choose a standard deviation method for calculating control limits. You can choose either Factors (R-Bar / d2) or Sample standard deviation. The Factors method provides the best prediction if your data exhibits more variation within subgroups than between subgroups, while the Sample standard deviation method provides the best prediction if your data exhibits more variation between subgroups than within subgroups.

Choose a method for calculating standard deviation for other statistics. You can choose either Factors (R-Bar / d2) or Sample standard deviation. The Factors method provides the best prediction if your data exhibits more variation within subgroups than between subgroups, while the Sample standard deviation method provides the best prediction if your data exhibits more variation between subgroups than within subgroups.

The method you choose will be used to calculate the Mean +/- 3SD, Mean +/- 4SD, 6SD, Zl, Zu, and Cpm for data in a normal distribution.

Statistical outliers are observations that violate SPC rules.

If you choose to exclude statistical outliers, the out-of-control data points will be displayed as outliers on control charts and on data tables but will be excluded from the statistical calculations.

To include all data points in the statistical calculations, choose All data included.
To exclude from the statistical calculations all data points that fall outside the calculated control limits, choose Data outside Control limits excluded.
To exclude from the statistical calculations all data points that fall outside the calculated control limits as well as data that violates SPC rules for runs, trends or zones, choose Out of Control, runs, trends and zone violations excluded.