The work wind does on the ocean can be computed by
where  is the chosen parameterization for the wind stress.
Thus, in resting ocean approximation, the work done on the ocean by the wind is
Furthermore, if the relative wind stress parameterization is used, the work done on the ocean is given by
Then, assuming  is the same in both situations, the difference between work done by resting ocean wind stress and relative wind stress is given by
Analysing this expression, we first see that the term  is always positive (since  and all the other terms are positive). Next, for the term , we have: 
* if  then  and so the overall sign is positive.
* if  then  and again, the overall sign is positive. 
Therefore, it is always the case that , meaning the calculation of the work done is always larger when using the resting ocean wind stress. This overestimate is referred to in the literature as a "positive bias". Note that this may not be the case if the   used in the calculation of  is different from the  used in the calculations of  (See section: Ocean currents as output of ocean models).