Symptom
Calculated rating showing in the form is incorrect based on the average rating formula which is the summation of rating times weight. The ratings are coming only from one section of the form for instance the goal section of the form.
Environment
 SAP SuccessFactors Performance Management
Reproducing the Issue
Lets take a screnario as below:

Ratings are only from the Goal section of the form with 100% section weight.
 Below are the 12 goal ratings and weights:
Rating Weightage
====== =======
6.0 10.0%
6.0 10.0%
4.0 10.0%
4.0 10.0%
4.0 15.0%
10.0 2.5%
5.0 5.0%
7.5 2.5%
5.0 10.0%
8.0 10.0%
3.0 5.0%
7.0 10.0%
 Calculated rating shows 6.47 instead of 5.44 following the average formula.
Cause
Goal section has a different rating scale used in the form. The rating will be normalized to the main rating scale configured in the form.
Resolution
The Calculated Rating that will be displayed in the form is the normalized rating. The calculated rating using the goal rating scale will be normalized to the main rating scale of the form.
Below is explanation how it works for the example scenario above.
Main Rating Scale of the form: (4,6,7,8,9)
Rating Scale of the Goal Section: (1,1.5,2,2.5,3,3.5,4,4.5,5,5.5,6,6.5,7,7.5,8,8.5,9,9.5,10)
Normalization Formula: (Rating  Section_ScaleMin) / (Section_ScaleMax  SectionScaleMin) = x
Normalized Rating = x * (ScaleMax  ScaleMin) + ScaleMin
where Rating= Rating calculated using the average formula (5.44)
Section_ScaleMin = Minimum rating of Section rating scale
Section_ScaleMax = Maximum rating of Section rating scale
ScaleMax = Maximum rating of Form rating scale
ScaleMin = Minimum rating of Form rating scale
In this case, the calculation goes as below:
(5.44  1.0) / (10  1) = (4.44 / 9 ) = 0.4933333
0.493333 * (9  4) + 4 = 6.466666
Hence the overall calculated rating is displayed as 6.47
See Also
2078768  Ratings; Understanding How Scores use Rounding; Scale Adjustments; Normalizations; Decimal Places  Performance Management
Keywords
Calculated overall performance rating Performance rating Wrong overall rating normalization , KBA , LODSFPMRAT , Ratings and Weightings , Problem