Page 186 - Bruce Ellig - The Complete Guide to Executive Compensation (2007)
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172               The Complete Guide to Executive Compensation


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                                                Job Value
            Figure 5-1. Pay and job value scattergram

               This data is then converted into grades by first identifying the cutoffs on the X axis
            that would seem consistent, given any clustering of similarly valued jobs, as shown in
            Figure 5-2.

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                                                Job Grades
            Figure 5-2. Conversion to job grades

               Next, a regression analysis is performed on the data to describe the line of best fit. This
            may be either a linear formula (which will force a straight line regardless of the format) or a
            nonlinear formula (which will describe the simple curve best reflecting the data). A nonlin-
            ear formula will result in a straight line only if all the plots truly describe a straight line. We
            will not take the time to perform the necessary calculations; the specific methodology for
            calculating the line (or curve) may be found in almost any statistics book. However, it is
            important to know the formula values.
               The formula for a linear regression analysis is Y   a   bX. The a is the value on the ver-
            tical or Y axis when X equals zero. The b describes the scope of the curve, in other words, the
            extent of increase in the Y axis (e.g., compensation) resulting from a stated change in value of
            the X axis (in this case job points).
               The nonlinear formula is Y   a   bX   cX . The value of c indicates the rate of change
                                                    2
            in the slope of the curve. A positive value indicates an increasing rate of change; a negative
            or minus c value indicates a decreasing rate of change.
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