论文标题

使用定期更新多级吸收马尔可夫链来提高毕业率的估计

Improving Graduation Rate Estimates Using Regularly Updating Multi-Level Absorbing Markov Chains

论文作者

Boumi, Shahab, Vela, Adan

论文摘要

美国大学使用基于六年毕业率的程序来计算有关学生最终教育成果(毕业或不毕业)的统计数据。作为〜六年毕业率方法的替代方法,许多研究应用了马尔可夫链以估计毕业率。在这两种情况下,都使用了常见的方法。对于〜标准的六年毕业率方法,频繁的方法对应于计算在六年内完成计划的学生人数,并除以那年进入的学生人数。在吸收马尔可夫链的情况下,使用频繁的方法来计算基础过渡矩阵,然后将其用于估计毕业率。在本文中,我们采用灵敏度分析来比较标准的六年毕业率法与吸收马尔可夫链的性能。通过分析,我们强调了在大学应用于小型样本量或同类群体时两种方法的估计准确性的重大局限性。此外,我们注意到吸收的马尔可夫链方法引入了明显的偏见,从而导致了对真实毕业率的低估。为了克服这两个挑战,我们提出并评估定期更新多层次吸收的马尔可夫链(Ruml-AMC)的使用,其中过渡矩阵逐年更新。我们从经验上证明,所提出的RUML-AMC方法几乎消除了估计偏差,同时将估计变化降低了40%以上,尤其是对于样本量较小的种群而言。

American universities use a procedure based on a rolling six-year graduation rate to calculate statistics regarding their students' final educational outcomes (graduating or not graduating). As~an alternative to the six-year graduation rate method, many studies have applied absorbing Markov chains for estimating graduation rates. In both cases, a frequentist approach is used. For~the standard six-year graduation rate method, the frequentist approach corresponds to counting the number of students who finished their program within six years and dividing by the number of students who entered that year. In the case of absorbing Markov chains, the frequentist approach is used to compute the underlying transition matrix, which is then used to estimate the graduation rate. In this paper, we apply a sensitivity analysis to compare the performance of the standard six-year graduation rate method with that of absorbing Markov chains. Through the analysis, we highlight significant limitations with regards to the estimation accuracy of both approaches when applied to small sample sizes or cohorts at a university. Additionally, we note that the Absorbing Markov chain method introduces a significant bias, which leads to an underestimation of the true graduation rate. To~overcome both these challenges, we propose and evaluate the use of a regularly updating multi-level absorbing Markov chain (RUML-AMC) in which the transition matrix is updated year to year. We empirically demonstrate that the proposed RUML-AMC approach nearly eliminates estimation bias while reducing the estimation variation by more than 40%, especially for populations with small sample sizes.

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