青年勞動者的轉銜經驗與社會脈絡相互交織，深刻影響著日後的生命軌跡，尤其在後高等教育擴張時代，愈發平等的高等教育機會非但未能弭平生命機會的歧異，反而促成了水平領域的階層化，初職薪資的不均已從原先的教育年限之差轉為STEM（科學、技術、工程和數學）和非STEM之間的領域之別；是以本文假探詢高等教育勞動者內部的領域階層，回應當代依舊僵化的薪資階層化命題。

本文採人力資源調查，以臺灣1978年至2021年間30歲以下的高等教育勞動者樣本進行分析。臺灣於1990年代經歷了第二次高等教育擴張，非 STEM 大學畢業生成為擴張的主要來源，然而在勞動市場職業結構則呈現相反的成長趨勢，STEM 領域職業所佔的比例逐漸增長，如是勞動力輸入與職位變化，形塑了高等教育勞動者內部的異質性，深化了領域間的階層化。

研究結果顯示，擁有STEM學位者在勞動市場中確實擁有薪資優勢，並透過進入具有證照系統的工作實踐職業封閉。若勞動市場是由更高比例的STEM勞動力投入和STEM職業所組成，則對所有青年勞動者的薪資皆有所助益。然在勞動市場世代層次亦發現高密度的STEM職業結構如同雙面刃，一方面高等教育勞動者得雨露均霑，另一方面也加劇了勞動者內部的薪資不均。隨著世代推移，STEM職業的比例日漸上升，高等教育青年勞動者的內部異質性或將日益擴大。

綜言之，即便皆為高等教育勞動者，實際上他們所面臨的勞動市場殊異，尋職情境大相逕庭，儘管教育端常為輿論針砭的對象，職業結構的影響不容忽視。此外，鑑於STEM和非STEM領域之間日漸彰顯的處境差異，政府當作為教育與勞動市場兩面的調和者，平衡經濟成長所致的矛盾。

In the post-expansion era, rising wage inequality can no longer be fully explained by years of schooling alone and has intensified along the lines of the field of study. STEM and non-STEM young college entrants face dynamic and heterogeneous transition scenarios, and their college degrees pay off to a divergent extent.

To disentangle the current stratification puzzle, I explore the wage disparity within the asymmetrical labor market scenarios for STEM and non-STEM young entrants using evidence from Taiwan. In the 1990s, Taiwan experienced the second wave of higher education expansion. This expansion was non-STEM-leaning; however, the occupation structure has grown biased toward STEM, leaving STEM entrants with a promising future but imposing profound disadvantages on those in non-STEM fields. The dataset derived from the Manpower Utilization Survey provides a comprehensive 44-year snapshot of college-educated (and above) entrants aged below 30, allowing me to construct variables at the occupational level (i.e., Linkage Strength and Licensed Occupation) and the labor-market cohort level (i.e., Relative STEM Worker Input and Relative STEM Occupation). Based on these variables, I employ multilevel mixed-effects linear regression models weighted by inverse propensity scores to investigate the wage payoff.

Mirroring prior literature, the empirical results indicate that, at the individual and occupational levels, STEM degree holders earn more than their non-STEM counterparts due to four rationales: the selectivity of return expectations and academic aptitude, gendered devaluation bias, specific human capital, and occupational closure through licensure. At the labor-market cohort level, both higher compositions of STEM college labor and occupations are beneficial for all. Nevertheless, a trade-off emerges—a higher composition of STEM occupations will deepen the wage inequality within the college workforce. Further inferring from a temporal perspective, I suggest that this heterogeneity may continue to widen due to the rising tendency of STEM occupations.

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