Understanding the Statistical Matrix

The statistical matrix is a spreadsheet view of various statistics that you can customize to include any statistic that Quality calculates. You can display the statistics in various formats.

Some statistics may be altered through the use of non-normal distribution assessment techniques. Quality incorporates the following methods to achieve an appropriate distribution fit. Both methods use the Pearson family of distributions.

• A test of normality, using the skewness and kurtosis of the distribution.

  If the distribution is normal at a 95 percent confidence, then the data is evaluated based on the normal assumption. If the distribution isn't found to be normal at a 95 percent confidence, then the data is evaluated using the Pearson Best-Fit family of curves. This is the recommended method if you are unsure of the distribution type.

• Direct use of the Pearson Best-Fit family of curves.

  The routines determine the best-fit and adjust the statistics appropriately.