HP 3000 Manuals

HP ALLBASE/BRW Reference Manual

Standard Deviation 

A common computation in a report is to compute a Standard Deviation.  You
can compute a Standard Deviation for any HP ALLBASE/BRW numeric type.

Example 

For example, the Standard Deviation for a Real item X that occurs in a
report detail can be computed as described in the following steps.

To compute the Standard Deviation of a Real item X 

   1.  Define a Real layout calculated item XSQUARE with this formula:

                  sqr(X)

   2.  Define an Integer layout calculated item XCOUNTER which will be
       used to count the number of details in a break.  The formula for
       this item is unimportant, as it is only to be used with a ColCalc
       value COUNT, to count the number of details.

       Use a 'dummy' formula such as:

            1

   3.  Define a Real layout calculated item STDEV with the formula:

       sqrt((XSQUARE - sqr(X) / XCOUNTER) / (XCOUNTER - 1))

   4.  Define these items on the break footer lineset:

            X             TOTAL
            XSQUARE       TOTAL
            XCOUNTER      COUNT
            STDEV         CALC

       This will compute the Standard Deviation for the Real item X
       within the break.

Related Sections 

   *   Calculations

   *   Formulas

   *   Numbers

MPE/iX 5.0 Documentation