Semester Award Granted

Spring 2025

Submission Date

May 2025

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Thesis/Dissertation Advisor [Chair]

Robert Shockley

Abstract

Doctoral-granting institutions invest time and resources to support the success of their Doctor of Philosophy (PhD) students. Despite these efforts, doctoral attrition rates remain high. One measure used to understand doctoral attrition and completion rates is time-to-degree (TTD). In 2020, the median TTD from the start of graduate school increased to 7.5 years (National Center for Science and Engineering Statistics [NCSES], 2020b), highlighting the need for continued analysis of factors affecting TTD. This study used data from the 2021 Survey of Earned Doctorates (SED; NCSES, 2021a) to provide a more recent analysis of the relationship between TTD and both student and institutional characteristics.

Astin’s Input-Environment-Output (I-E-O) model served as the conceptual framework and helped guide the variables included in this study (Astin, 1970a; Astin & Antonio, 2012). The input variables included student characteristics (i.e., gender, race/ethnicity, age, marital status, dependents, citizenship status), while the environment variables consisted of institutional characteristics (i.e., Carnegie Classification, institutional control, field of study, financial support). TTD was the output or dependent variable. Both univariate and multivariate analyses were conducted to examine the relationships between the variables and TTD. The sample for this study included 49,358 PhD recipients from 448 public and private institutions across the United States.

The univariate analyses revealed statistically significant differences; however, the practical significance of all student and institutional characteristics was relatively small. When student and institutional characteristics were combined, the multiple linear regression showed that the model was significant, accounting for approximately 9.9% of the variance in TTD. When the subset of student characteristics was added to the model that included institutional characteristics, the model was significant, with a change in R² of 1.4%. Similarly, when the subset of institutional characteristics was added to the model that included student characteristics, the model was significant, with a change in R² of 5.3%. This indicates that institutional factors contributed more to the model than student factors.

Although this study confirmed the relationship between TTD and both student and institutional characteristics, these factors had a relatively small influence, whether individually or combined. Due to the low predictive power, other, more nuanced factors may provide better insights into what drives PhD degree completion times. These findings should encourage institutions and policymakers to adopt more holistic strategies to foster doctoral student success.

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