台灣地區個人薪資所得不均度從1989年起逐年上升,分析這段期間不均度上升的原因是本文的主旨。我們利用「因素分析」法把複雜多樣的勞動市場,簡化成兩種技能屬性的市場,各種勞動力的差異,在於他們擁有兩種技能數量的不同。我們再把薪資所得表成這兩種技能的數量和價格的函數,每種勞動力擁有的技能數量在各年間固定不變,但是技能價格決定於該技能的供給和需求,會隨著時間改變。於是兩期之間的薪資所得不均度便可以分解成需求因素、供給因素、因素分析殘差項、和迴歸殘差項的四種貢獻。本文的實證研究發現:造成1989-2000年間薪資所得不均度上升的主因是需求因素的變化,其貢獻約佔52%。另外,供給因素亦為不均化因子,其貢獻約為28%。
This study explains the rising trend of wage income inequality in Taiwan since 1989. A factor analysis is applied to Taiwan's labor market, where workers distinguish themselves from others by their endowments of unobservable ”skills”. Wage income therefore can be expressed in terms of “'skill price” and “'skill endowment”. “Skill price” is determined by demand factors (e.g., unemployment rate, the ratio of export to GDP), and supply factors (i.e., the relative quantity of that skill in the economy.) In so doing, the intertemporal changes in wage income inequality can be decomposed into the contributions of demand factors, supply factors, and residuals. This study finds that both demand and supply factors are inequalizing factors. Their contributions to the rise in wage income inequality during the 1989-2000 period are 52% and 28%, respectively.