恆毅力對於高等教育學習成果之影響及群間差異的非線性分解方法改善

Two Essays on Grit Effect in Higher Education and A Refinement of Nonlinear Decomposition on Group Difference

黃鼎恩(Ding-En Huang)

指導教授 ： 林世昌

國立清華大學/科技管理學院/經濟學系/博士(2020年)

摘要

人力資本累積帶來經濟成長動能，但隨著台灣的高等教育逐漸面臨縮減與整併，以及少子化導致的大學人數遞減的現象，高等教育在未來是否仍能帶來充足的人力資本累積，是個值得關注的議題。本文第一份研究，依據 Duckworth et al. （2007）所提出的恆毅力指標，並利用國立清華大學的學生資料，發現恆毅力兩構面中的毅力對個人在高等教育體系中獲取知識、運用知識及創新能力的人力資本累積都有正面影響，作為另一構面的熱情對人力資本累積的影響則正負並陳，甚或不具影響。此外也透過將學生按照毅力與熱情的高低程度分成四組，以各組的累積人力資本表現為基準，找出表現最優勢與最劣勢的組別後，探索造成這二組學生之間表現差異的可能因素。在利用 Blinder-Oaxaca 分解法並解決樣本選取問題後，發現學習習慣的良莠是造成這二種學生在累積人力資本的表現上有所差異的部分原因。此外，也發現在眾多的個人特質與家庭背景等因素中，除了就讀大學的內在誘因對恆毅力有正面影響外，其餘影響毅力與熱情的因素是互不重疊的。

恆毅力在實證上所獲得的支持並不一致，將恆毅力量表作為單一指標時，其對個人表現大部分有正面影響，但也有一些負面影響的案例。另外，當把恆毅力量表分為兩個構面，個別探討其對個人表現的影響時，毅力常有正面影響，而熱情卻有正負並陳的影響，甚或不具影響。針對此現象，文獻上認為既有的橫毅力指標可能並沒有完整地捕捉到其所定義的熱情。因此，本文的第二份研究提出了衡量熱情的新指標，此指標較偏重衡量學生對學習的熱情，並與恆毅力量表之毅力及熱情一同評估對大學生的在校表現影響。結果顯示出學習熱情對本研究採用之四種學習表現皆有正面影響，毅力對其中三種學習表現有正面影響，而熱情的影響則正負並陳，甚或不具影響。此外，學習熱情與熱情皆對讀取碩士以上學位的意願有正面影響，但僅有學習熱情對讀取博士學位的意願有正面影響。此外，隨著學生長期對學習越能保持熱情，其毅力的提升對學生的學習成果有更大的正面影響。上述結果皆顯示出對恆毅力效果的正面支持。

分解群間的目標變數差異並分析其組成，在諸多議題的研究中皆可看到其應用，如男女薪資不均或種族間創業比例失衡之原因。然而在探索非連續型的量化變數於群間差異之構成因素時，在文獻上並沒有一致的方法，且各種方法皆有其優缺點。以 Fairlie （1999）為例，由於其運算過程涉及樣本選用皆具隨機性，導致其所得到之構成因素之數值亦為隨機結果。本文第三份研究頗析 Fairlie （1999）的分解方法，並以此為基礎提出一套新的分解方式，運算過程及樣本選用皆不具隨機性，因此得到穩健的分解結果。此外，亦將此方法與其他既存方法套用到模擬資料及實證資料，分解之結果顯示出本研究所提出之方法所得到之結果相較其他分法更為穩健，可作為研究者衡量各種因素對群間的目標變數差異所造成貢獻進行量化的比較基準。

關鍵字

恆毅力 ； 人力資本 ； 高等教育 ； 學習表現 ； 分解 ； 二元變數 ； 群間差異

並列摘要

Accumulation of the human capital boosts economic development. In Taiwan, higher education is facing downsize, and the amount of students entering higher education is also decreasing due to the falling population of children. Along with these phenomena, whether the supply of human capital from higher education can remain its sufficiency as usual is a crucial issue of concern. The first research in this dissertation uses the data of students of an elite university in Taiwan to assess the role of the grit (a psychological personality hypothesized to affect an individual's achievement) in students' performance of accumulating the human capital. Among two facets of the grit, perseverance positively influences the accumulation of human capital in a higher education system, while the effect of passion (the other facet of grit) depends on the learning outcome of interest, which can be either positive, negative, or non-influential. Also, by splitting students into four groups by their level of perseverance and passion, we identify the advantaged and disadvantaged groups by choosing the groups respectively with the highest and the lowest proportion of students that have experienced the accumulation of human capital among four groups. By using Blinder-Oaxaca decomposition along with Heckman's correction term to selection bias, we find the better learning habits to be a partial reason the advantaged students can have better performance than the disadvantaged students in terms of the probability of accumulating the human capital. Moreover, we find, among the personal characteristics and family background of the student, that the factors that are influential to perseverance and passion diverge, with the exception of the intrinsic incentives to study at university, which has a positive influence on the perseverance and passion of an individual.

However, the evidence for the grit effect from previous studies is conflicting. When using the grit as one factor, the grit's effect on an individual's performance can either be positive, negative, or even not statistically significant. Besides, the perseverance of grit is always positively influential to the individual's performance, while the effect of passion can either be positive, negative, or not statistically significant. Some researchers have criticized the grit scale proposed by Duckworth et al. (2007) fails to capture what is defined. Therefore, the second study of this dissertation proposes to use alternative metrics of passion that are close to what Duckworth et al. (2007) define, but these new metrics are more domain-specific to students' passion for learning in the long term. Empirical results show the newly used measures of passion have a positive impact on the four measures of learning outcomes used in this study, while perseverance (measured on a grit scale) has a positive effect on only three of the four learning outcomes. Furthermore, the sign of passion's impact (measured on the scale of grit) depends on the outcome variable of interest, which can be either positive, negative or not statistically significant. In addition, both the newly-used passion and the passion by the grit scale have positive influence on an individual's intention to study for a master's degree or higher degree, but only the former affects the intention to obtain a doctorate degree. Finally, increasing an additional unit in perseverance has a greater effect on a student's learning performance, as the individual can sustain his or her passion for learning in the long term.

Decomposing the gap between groups and analyzing the components inside the gap is a widely used technique in economic research, such as exploring the potential causes to the gender pay gap or the racial gap in self-employment rate. Although there are various methods proposed to decompose the between-group gap in a qualitative outcome variable, each method has its advantages and disadvantages. Fairlie (1999), for example, suggests a simulated algorithm to generate a detailed decomposition for such a gap, but the result of this approach is random due to the entire calculation, which involves randomness in several steps. The third research is working on the revision of Fairlie (1999)'s algorithm and proposes a new approach called GEWE, which does not involve randomness in the calculation and thus provides a robust result of decomposition. Also, GEWE along with other approaches are all applied to the simulated data and the empirical data, and the results suggest the GEWE to be an acceptable benchmark for users to analyze and quantify the potential cause to the between-group gap in a binary outcome variable.

並列關鍵字

grit ； human capital ； higher education ； learning outcome ； decomposition ； binary variable ； group difference

參考文獻

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