A Note on Precision

An Extended precision calculations check box is available on the Options tab of the Descriptive Statistics and Product-Moment and Partial Correlations dialog boxes. Statistica employs proprietary extended precision algorithms in order to minimize round-off error in the computations. Select the Extended precision calculations check box if the variables in the analysis show extremely small relative variances (variance divided by the mean); for example, if all values for a variable range between 10000.000001 and 10000.000002 (note that there is a difference between small variance and small relative variance; e.g., the relative variance of values in the range of .0000000000000001 to .0000000000000002 is not small). For large data files with many thousands of cases, the computations may be somewhat slower when you select the Extended precision calculations check box.