臺灣基本工資調升對薪資不均之影響──2012-2019實證

THE IMPACT OF MINIMUM WAGE ON WAGE INEQUALITY IN TAIWAN: EVIDENCE FROM 2012-2019

臺灣2012至2019年名目基本工資逐年調升，實質基本工資逐年靠近第50百分位數薪資水準，薪資分配底端（lower tail）的薪資不均度逐年下降，本研究探討此期間基本工資調漲對薪資分配底端薪資不均度下降之影響。薪資不均度之衡量為log各百分位數薪資水準與log第50百分位數薪資水準（薪資中位數）之差距。本研究參考Lee（1999）之模型，利用有效基本工資（log基本工資與log薪資修剪均數（trimmed mean）之差距）之跨縣市變動，認定（identify）基本工資對薪資不均之影響。估計結果顯示臺灣2012年至2019年期間基本工資逐年調升，幾乎解釋了所有第10百分位數薪資不均度之下降，基本工資每調升5％，薪資第10百分位數薪資不均度顯著下降2.685％，同時，基本工資亦顯著影響薪資第20、30、40百分位數薪資不均，此影響隨百分位數的提高而減少；相對地，基本工資對薪資第60至90百分位數（高所得）薪資不均度並無顯著之影響，此驗證了Lee（1999）模型之認定假設（identification assumptions）適用於臺灣薪資分配資料之分析。

During 2012-2019, minimum wages in Taiwan were raised annually and the wage inequality of the bottom half of the wage distribution decreased substantially. This study investigates the association between the raising of the minimum wage and the decrease in lower-tail wage inequality in Taiwan by using the data of the Manpower Utilization Survey of DGBAS (Taiwan). The wage inequality is measured as the difference between the log of the p^(th) percentile wage and the log of the 50^(th) percentile wage in the wage distribution. This study uses the cross-county variation in effective minimum wage to identify the impact of minimum wage on wage inequality. The results show that the raising of the minimum wage during 2012-2019 accounts for the entire drop in the 10^(th) percentile wage inequality. As minimum wage was raised 5%, the 10^(th) percentile wage inequality dropped 2.685% accordingly. Meanwhile, the raising of the minimum wage was significantly associated with decreases in the 20^(th) to 40^(th) percentile wage inequality with decreasing rates. In constrast, minimum wages show insignificant impact on the 60^(th) to 90^(th) percentile wage inequality, which justifies the identification assumption used in this study.