The Development and Solution of a Tax-Adjusted Model for Personal Injury Awards: A Clarification
指出Brady等人1984年提出的税收调整模型在求解时存在模糊性，并澄清了通过结合方程与税率表可得到唯一解，对从事人身伤害赔偿评估的精算师和法律从业者有参考价值。
In the March 1984 issue of this Journal, Brady, Brookshire and Cobb [1984] developed a tax-adjusted model for injury awards. On page 40, directly following equation (7), the authors state the following: Since only two unknowns exist in equation (7), the starting lump sum in the last year can be easily found.' This statement is very disturbing in that a unique solution does not exist if the number of unknowns exceeds the number of equations. The authors go on to explain an iterative technique used to obtain a solution. The iterations involve successive estimates of the effective tax rate on lump sum interest earnings in the final period. They fail to indicate the source of these estimates which would represent the second equation necessary for a unique solution. The reader can only conjecture that the tax estimates are obtained from a tax rate table. The total of the starting lump sum and the interest allows one to find the marginal tax rate. This marginal tax rate is then used in equation (7) to find a new starting lump sum for each iteration. The interest on this new starting sum is then used to find a new marginal tax rate. A solution is found when the interest is not sufficient enough to hike the individual into a higher tax bracket. Subsequently, equation (7) would provide the same starting lump sum as the previous iteration and therefore the same interest and the same marginal tax rate. While the authors do agree with the general injury valuation model presented by Brody, Brookshire and Cobb the outlined solution to the model is unclear. When the reader recognizes that BBC have two equations, their equation (7) and a personal tax table equation, a unique solution does exist to the model.