The Role of Department Supports on Doctoral Completion and Time-to-Degree

Abstract

This study examined department supports that influence doctoral completion and time-to-degree among 5,001 doctoral programs at 212 universities in the United States. Multiple regression models were used to determine the relationships between financial support and academic support and doctoral retention and how these relationships vary across STEM and non-STEM fields. Analyzing the American National Research Council’s data, we found that a department’s financial support significantly predict doctoral completion and time-to-degree. However, no overarching relationship was found between department academic support and doctoral completion and time-to-degree. These findings provide a better understanding of how department supports are associated with doctoral student success. The article concludes with implications for theory, practice, and future research.

Keywords

department support doctoral completion time-to-doctorate

Despite the vast contributions of doctoral students, doctoral education, and doctoral degree holders, relatively little is known about degree completion in doctoral programs. While the National Science Foundation’s Survey of Earned Doctorates keeps account of the number of earned doctorates, few studies identify how many of those who began pursuing doctoral degrees eventually have earned one. Golde (2005) found that only 60% of students who started a doctoral program in the United States successfully completed it. In addition, previous studies have found that doctoral completion rates vary across fields of study (Kim & Otts, 2010; Stricker, 1994; Sowell, Allum, & Okahana, 2015). Sowell, Zhang, Bell, and Redd (2008) found that the 10-year doctoral completion rates were approximately 64% in engineering, 63% in life sciences, and 56% in social sciences.

Several studies focus on doctoral completion and attrition; however, many have focused on student-level (Gardner, 2008; Golde, 1998, 2000; Maher, Ford, & Thompson, 2004; Seagram, Gould, & Pyke, 1998) or institutional-level factors (Ehrenberg & Mavros, 1995; Goenner & Snaith, 2004; Kim & Ottis, 2010). For example, many studies of doctoral completion have focused on the effects of student factors, such as student experience (Golde, 1998, 2000), student socialization (Gardner, 2008), and student demographic characteristics (Maher et al., 2004; Seagram et al., 1998). Other studies have investigated institutional-level factors, such as institutional characteristics (Kim & Otts, 2010), institutional expenditures (Goenner & Snaith, 2004), and institutional financial support (Ehrenberg & Mavros, 1995) on doctoral completion. Yet, few have studied how departmental or program characteristics relate to student completion of doctorates. Furthermore, most studies on doctoral retention have focused on a few institutions or programs (Golde, 2005; Herzig, 2002; Malone, Nelson, & Van Nelson, 2004); thus, their findings may not be generalizable to the entire doctoral population in the United States.

This study addressed these two gaps in the literature by using a national data set that captured aggregated doctoral completion rates and characteristics of doctoral departments or programs. The aim of this study was to understand departmental or program characteristics and factors that might be associated with doctoral completion. Specifically, the present study examined how department financial support and academic support related to doctoral completion by exploring the following research questions: (a) Are department financial support and academic support positively associated with doctoral completion? (b) Are department financial support and academic support positively associated with time to doctoral degree? and (c) Do financial support and academic support influencing doctoral completion and time-to-degree vary between STEM and non-STEM fields?

Review of Relevant Literature

Traditional understanding of doctoral retention and completion are drawn from Tinto’s (1975) retention theory, which intended to explain undergraduate student retention through social and academic integration. Girves and Wemmerus (1998) further expanded Tinto’s retention theory and articulated a conceptual framework for graduate school process and doctoral retention and completion. This framework contended that doctoral degree progress was shaped by four factors: program characteristics, financial support, faculty characteristics, and student involvement.

Financial Support and Doctoral Retention

Many studies on doctoral retention and completion have focused on financial support for graduate students and generally suggest positive correlations between availability of financial support and increased persistence and timely completion of doctoral degree. Financial support and the course work–research relationship were positively associated with higher completion rates and shorter doctoral time-to-degree (Valero, 2001). In a study that examines the relationships between various types of financial support and doctoral retention, Mendoza, Villarreal, and Gunderson (2014) found that research assistantships and teaching assistantships were positively associated with within-year doctoral persistence. Moreover, Ehrenberg and Mavros (1995) found that having fellowships or research assistantships was associated with higher doctoral completion rates and shorter time-to-degree, compared with having teaching assistantships or tuition waivers. Similarly, in a study examining the effect of financial aid on doctoral completion, Ampaw and Jaeger (2012) found that students with research assistantships were more likely to earn their doctorates compared with those with other forms of financial support. The amount of fellowships or grants also related to doctoral time-to-degree (Gillingham, Seneca, & Taussig, 1991). In addition, doctoral students with research assistantships were more likely to get research-related jobs after graduation, compared with students who are funded by fellowships (Blume-Kohout & Adhikari, 2016).

Academic and Faculty Support and Doctoral Retention

Another factor of doctoral retention that is discussed widely in the literature is socialization in disciplines (Gardner, 2010; Gardner & Barnes, 2007). Prior studies found that positive and productive interactions with their peers, faculty members tend to increase likeliness that students persist and eventually earn their doctorates. Positive student–faculty relationships facilitated integration of students into disciplines and academic departments, which was an important factor for doctoral retention and completion (Cockrell & Shelley, 2011; Golde, 2000; Valero, 2001). Integration and involvement in disciplines (Golde, 2005; Herzig, 2002) and academic departments (Golde, 2000; Herzig, 2002) were an integral part in retention of doctoral students. Close and productive faculty–student relationship as well as communication and selection of dissertation committee members were key factors for successful and timely completion of doctorates (Barnes, 2009; Wao, Dedrick, & Ferron, 2011; Wao & Onwuegbuzie, 2011). Thus, it is not surprising that department academic support such as supporting groups were important program factors which associated with doctoral student success (Gardner, 2008; Greene, 2015). Department activities and department attitudes toward students were positively related to doctoral completion (Valero, 2001). In addition, students participating in engagement activities such as student groups and associations experienced positive outcomes in lowering graduate students’ stress and improving completion (Kearns, Gardiner, & Marshall, 2007). However, Golde (2000) also found that departmental academic support for doctoral students vary by disciplines. Thus, the literature must expand to look at various fields of study to examine more robust effects of departmental academic support.

Other Factors

In addition to student socialization in academic departments, prior studies have suggested that student compositions and other departmental characteristics such as program size, student–faculty ratio, and fields of study may affect doctoral retention and completion. A smaller department size was associated with shorter times-to-degree for doctoral students (Stricker, 1994), and likewise student–faculty ratios and percentage of full-time faculty were significant factors in explaining graduation rates (Goenner & Snaith, 2004). Faculty advisers were indeed influential to doctoral student experience (Zhao, Golde, & McCormick, 2007), in particular in the STEM fields (Joy, Liang, Bilimoria, & Perry, 2015). Doctoral experience and attrition (Gardner, 2009, 2010) as well as time-to-degree (Gillingham et al., 1991; Seagram et al., 1998) also differ by fields of study. In an analysis of doctoral student attrition in the STEM fields, Lott, Gardner, and Powers (2009) found that STEM students who were females, Asians and majoring in hard-applied science were less likely to be retained. Moreover, student demographics such as gender (Maher et al., 2004; Seagram et al., 1998), race, and citizenship (Stricker, 1994) were program characteristics associated with doctoral completion. Doctoral programs with a higher percent of international students were more likely to have higher completion rates and shorter time-to-degree (Ampaw & Jaeger, 2012).

Furthermore, several studies have examined these factors more holistically. A recent study, though it was a single-institution research, found that program structure, faculty support, and research engagement were key factors that related to doctoral retention (Bagaka’s, Badillo, Bransteter, & Rispinto, 2015). Similarly, Ehrenberg, Jakubson, Groen, So, and Price (2007) found that financial support, department culture, and faculty advising were factors associated with doctoral retention, and Ivankova and Stick (2007) found that program quality, student support, and faculty characteristics were three critical factors contributing to doctoral degree progress. However, these studies are limited to a few disciplines (Ehrenberg et al., 2007; Stricker, 1994; Wao et al., 2011) or a few institutions (Ampaw & Jaeger, 2012; Bagaka’s et al., 2015; Seagram et al., 1998).

Understanding how departmental financial support and academic support relate to doctoral student retention is important, and potential implications are great for practice and policy surrounding doctoral education. Most studies on doctoral student retention and completion have limited scopes of institutions, programs, and fields of study, thus not generalizable to the doctoral education community as a whole. This study attempts to fill the gap by using a national data set on departmental or doctoral program characteristics. Results of this study contributed to the doctoral study literature and improved practice by providing administrators and policy makers with new empirical evidence that employed a national data set.

Research Methods

Data and Sample

The current study employs the National Research Council (NRC)’s A Data-Based Assessment of Research-Doctorate Programs in the United States. The data were collected from 5,001 doctoral programs at 212 doctoral research universities in the United States for the 2005/2006 academic year. These doctoral programs were disaggregated into six broad fields of study: (a) agricultural sciences, (b) biological and health sciences, (c) engineering, (d) physical and mathematical sciences, (e) social and behavioral sciences, and (f) humanities. The data provided information at the doctoral departmental level including program characteristics, faculty characteristics, research productivity, student support, as well as program outcomes (NRC, 2011).

Outcome variables

To address the research questions, this study focused on two outcome variables of interests: aggregated cohort doctoral completion rates and median times-to-doctorate. The data set included aggregated cohort completion rate of both full-time and part-time students for each doctoral program. Cohort completion rates were calculated as 8-year completion rates for humanities students who entered in their doctoral programs between academic years 1996/1997 and 1998/1999. For other fields of study, 6-year cohort completion rates were calculated for those students who begun their doctoral studies between academic years 1996/1997 and 2000/2001. In the data set, completion rates were expressed as percentage points. Each doctoral program in the data set also reported the median time-to-completion for both full-time and part-time students who earned their doctorates between 2003 and 2005, and reported in terms of the number of years.

Independent variables

This study focused on two indicators of department support: financial support and academic support for doctoral students. Financial support variables included the percent of doctoral students with research assistantships, the percent of doctoral students with teaching assistantships, the percent of doctoral students with fellowships, and whether a department provided health insurance and travel support to attend professional meetings for graduate students. Doctoral programs included in the data set computed percentage points based on the total number of doctoral students enrolled in their programs in Fall 2005. Health insurance and travel support were measured by dichotomous variables indicating whether a department provided graduate student health insurance and whether a department provided travel support. Academic support variables included four dichotomous variables, indicating whether or not a department provided student work space, training in writing, training in teaching, and whether a department had a graduate student association or not.

Control variables

Aligned with previous research and theoretical framework, we controlled for two sets of department factors in this study: program characteristics and faculty characteristics. Program characteristics included variables found to be important in studies of doctoral retention, such as program size (Stricker, 1994), average GRE scores (Malone et al., 2004), institutional control, and student demographics. Program size was measured by the average annual first-year enrollment from 2002 to 2006 and was a continuous variable measuring the number of first-year students enrolled in the department. Institutional control was a dichotomous variable (public university = 1 and private, not-for-profit university = 0). Demographic compositions of doctoral programs included the percent of non-Asian minority students, the percent of female students and the percent of international students. The non-Asian minority students was computed by the number of American Indians, Alaska Natives, African American, and Hispanic students divided by the total number of domestic students. The female student and international student variables were the percent of the total number of graduate students in Fall 2005, and they were continuous variables.

Faculty characteristics variables in this study included faculty demographics and faculty research productivities. Faculty demographic variables included the number of faculty, the percent of non-Asian minority faculty, the percent of female faculty, and the percent of tenured faculty in a department. The four faculty demographic variables were percentages of the total number of faculty in 2006, and they were continuous variables. Faculty research productivity was indicated by the variables of faculty publications, citations, grants, and awards. Publication variable measured the average number of publications per faculty from 2000 to 2006. This variable was calculated by the number of articles each faculty member published divided by the total number of publications for all faculty in the department. Faculty citation was measured by the annual average of citations over 7 years (2000–2006) by faculty divided by the sum of publications of the programs. Faculty grant variable was measured by the number of faculty with external grants divided by the total number of faculty in 2006. Faculty award was measured by the total number of external awards and honors of all faculty divided by the total number of faculty in 2006.

Description of Research Studies

Table 1 contains descriptive statistics of key variables used in this study by STEM and non-STEM fields. We found that among the 5,004 doctoral programs, the average doctoral completion was 45%, and the median time-to-degree was 5.76 years. Comparing program characteristics between STEM and non-STEM fields, students in the STEM field took less time to graduate (5.26 years) than students in non-STEM fields (6.64 years). The average completion percentages in STEM departments were higher (49%) than the completion rate in non-STEM fields (39%). Both STEM and non-STEM departments were in the large quartile in terms of program size and had an average of 48 students enrolled in the department. About 74% of the STEM departments were in public institutions compared with 68% of non-STEM departments.

Table 1.

Descriptive Statistics by STEM and Non-STEM Fields.

	All programs		STEM		Non-STEM
	Mean	SD	Mean	SD	Mean	SD
Program characteristics
Number of students enrolled	48.11	44.70	48.18	49.12	47.93	35.46
Average annual first-year enrollment	9.96	9.92	10.59	11.05	8.71	6.41
Institutional control	0.72	0.45	0.74	0.44	0.68	0.47
Percent of non-Asian minority students	0.12	0.14	0.11	0.13	0.13	0.14
Percent of female students	0.45	0.20	0.40	0.20	0.54	0.18
Percent of international students	0.36	0.25	0.43	0.24	0.23	0.21
Faculty characteristics
Average number of publications	3.29	5.36	1.68	1.16	6.04	7.23
Average citations per publication	2.16	1.51	2.39	1.57	1.40	0.95
Percent of faculty with grants	0.62	0.33	0.79	0.18	0.30	0.24
Awards per faculty member	1.01	2.15	0.87	2.29	1.25	1.84
Percent of tenured faculty	0.71	0.16	0.70	0.16	0.74	0.14
Financial support
Percent of students with research assistantships	0.27	0.50	0.37	0.28	0.08	0.15
Percent of students with teaching assistantships	0.23	0.26	0.18	0.23	0.33	0.27
Percent of students with fellowships	0.21	0.32	0.17	0.29	0.29	0.36
Travel support	0.99	0.11	0.98	0.13	1.00	0.06
Academic support
Is health insurance provided	0.86	0.35	0.86	0.35	0.86	0.35
Is student work space provided	0.67	0.47	0.79	0.41	0.45	0.50
Training in proposal writing	0.89	0.31	0.87	0.34	0.94	0.23
Has a graduate student association	0.97	0.16	0.97	0.18	0.98	0.12
Training in teaching	0.95	0.22	0.93	0.25	0.98	0.13
n	3,283		2,500		783

Students in STEM departments had a higher average of GRE scores (718 scores) than non-STEM students (637 scores). The average first-year students recruited by STEM departments (11 students) was higher than non-STEM departments (9 students). STEM departments had fewer non-Asian minority students (11%) than non-STEM fields (13%). Moreover, there were less female doctoral students in STEM departments (40%) than non-STEM departments (54%). There was a larger number of international students in STEM (43%) than non-STEM departments (23%).

Regarding faculty characteristics, the average number of publications and the average citations per publication of STEM faculty were 1.68 and 2.39. In comparison to the STEM departments, the average number of publications and the average citations per publication of non-STEM faculty were 6.4 and 1.4. There were more faculty who had grants in the STEM departments than the non-STEM departments (80% vs. 30%). The average number of awards per faculty was lower in STEM than non-STEM (0.87 vs. 1.25). The percent of tenured faculty in both STEM and non-STEM departments was about 70%.

For financial support, 37% of students had research assistantships, 18% had teaching assistantships, and 17% had institutional fellowships in the STEM departments. In non-STEM departments, 8% of students had research assistantships, 33% had teaching assistantships, and 29% had institutional fellowships. Most of departments regardless whether the STEM or not provided health insurance and travel support for doctoral students to attend professional meetings.

For department academic support, 79% of STEM departments provided work space for doctoral students, 87% of them provided training in writing, 93% of them provided help in teaching, and 97% of them had an active graduate student association. In the non-STEM departments, only 45% of them provided work space for students. However, non-STEM departments provided more resources on writing and teaching; 94% of them provided training in writing, 98% of them provided help in teaching, and 98% of them had an active graduate student association.

Data Analysis

The multiple regression models were used to identify the relationships between department supports and doctoral degree completion and time-to-degree (Tarling, 2009). Extensive research has shown that doctoral completion and time-to-degree were different by fields of study (Baird, 1990; Golde, 2005; Kim & Otts, 2010; Stricker, 1994; Sowell et al., 2008, 2015; Xu, 2014). Therefore, to clarify if the relationship between doctoral completion and time to doctoral differs by disciplines, a separate set of multiple regression models was conducted in STEM and non-STEM fields. A group of the variables measuring the influence of department financial and academic supports of the whole sample were entered into the regression models.

To account for the doctoral completion differences across disciplines, we categorized departments into the STEM fields and the non-STEM fields. The STEM fields included agricultural sciences, biological and health sciences, engineering, physical, and mathematical sciences. The non-STEM fields included humanities and social and behavioral sciences. The total sample size was (n = 5,001), with STEM fields (n = 3,205) and non-STEM fields (n = 1,796).

Model 1 analyzed whether department financial support and academic support were associated with doctoral completion for all the programs. The probability of average doctoral completion percentage was a function of the intercept terms plus financial support and academic support plus the covariates, which include program characteristics and faculty characteristics with coefficients plus the error terms. To analyze the department supports which associated with doctoral completion and time-to-degree in both STEM and non-STEM fields, we separated models by analyzing only programs in STEM (Model 2) and non-STEM fields (Model 3). In doing so, we examined whether doctoral completion and time-to-degree are affected by department supports and how the relationships differ by field of study. In the second set of regression models, we examined whether department supports were associated with doctoral time-to-degree. We replaced median time-to-degree as a dependent variable, other aspects remain the same for Models 1, 2, and 3. The data analysis was conducted in SPSS software. Missing data were deleted using listwise deletion. The final sample sizes in the models were as follows: all departments (n = 3,283), STEM (n = 2,500), and non-STEM (n = 783).

Limitations

This study contributed to the literature of department factors and doctoral student retention. However, we were limited to the variables existing in the data which were designed and implemented by the NRC. For example, our analysis did not include the amounts of fellowships, assistantships, and travel support offered to the students or frequency to which academic support were used by each student or on average. Also, doctoral program requirements were important factors that related to retention, but we did not account for these factors due to data limitation. Another limitation of this study was that student factors which may relate to doctoral student retention were not included in the models. The NRC data provided departmental observations; therefore, we were unable to control student characteristics variables such as age, role of responsibility, work experience, student–faculty relationship, student engagement, and perceptions. The unit of analysis in our study was department. However, the data still allowed us to examine how program characteristics may explain doctoral completion rates and times-to-degree in the most comprehensive way, using data from 212 institutions across the nation.

Results

Department Support and Doctoral Completion

All programs

Table 2 reported the regression results of department financial support and academic support on doctoral completion in all programs, STEM, and non-STEM programs. The coefficients indicated the magnitude of effect in probability (Tarling, 2009). Results of all programs (Model 1) indicated that providing doctoral student work space was more likely to increase completion rates compared with departments which did not provide work space. Among the involvement activities, only work space was a significant predictor of doctoral completion. However, the increasing percent of students with teaching assistantships was negatively associated with doctoral completion.

Table 2.

Regressions of Program Factors on Doctoral Completion in All Programs, STEM, and Non-STEM Fields.

	All programs			STEM			Non-STEM
	(1)			(2)			(3)
	B	SE	Sig.	B	SE	Sig.	B	SE	Sig.
Program characteristics
Number of students enrolled	0.00	0.00	***	0.00	0.00	***	0.00	0.00	***
Average annual first-year enrollment	0.00	0.00	***	0.00	0.00	***	0.02	0.00	***
Institutional control	0.00	0.01		−0.01	0.01		0.00	0.02
Percent of non-Asian minority students	−0.04	0.03		0.00	0.03		−0.07	0.06
Percent of female students	0.05	0.02	*	0.11	0.02	***	0.02	0.05
Percent of international students	0.08	0.02	***	0.06	0.02	***	0.05	0.04
Faculty characteristics
Average number of publications per faculty	0.00	0.00		0.00	0.00		0.05	0.02	*
Average citations per publication	0.00	0.00		−0.01	0.00	***	0.02	0.01	*
Percent of faculty with grants	0.13	0.02	***	0.06	0.03	*	0.07	0.04
Awards per faculty member	0.00	0.00		0.00	0.00		0.00	0.01
Percent of tenured faculty	−0.09	0.02	***	−0.05	0.03		−0.19	0.05	***
Financial support
Percent of students with research assistantships	0.00	0.01		0.03	0.02		0.07	0.04
Percent of students with teaching assistantships	−0.08	0.02	***	−0.10	0.02	***	−0.02	0.03
Percent of students with fellowships	−0.02	0.01		0.01	0.01		−0.05	0.03
Travel support	0.02	0.03		0.02	0.03		0.00	0.09
Is health insurance provided	0.00	0.01		0.01	0.01		−0.03	0.02
Academic support
Is student work space provided	0.05	0.01	***	0.02	0.01		0.05	0.02	***
Training in proposal writing	−0.01	0.01		0.00	0.01		−0.01	0.03
Has a graduate student association	0.00	0.02		0.01	0.02		0.05	0.05
Training in teaching	0.02	0.02		0.02	0.02		0.00	0.05

p < .05. **p < .01. ***p < .001.

STEM fields

In the STEM fields (Model 2), increasing the number of student activities was associated with higher science doctoral completion. A higher percent of students with research assistantships and fellowships was positively related to completion. However, the percent of students with teaching assistantships was negatively associated with STEM doctoral completion. Providing work space, training in writing and teaching, as well as having a graduate association were positively associated with STEM doctoral completion. However, none of these student involvement variables were statistically significant.

Non-STEM fields

Model 3 presented regression results for non-STEM departments. None of the financial supports and student involvement variables had statistical significant relationships with non-STEM doctoral completion except providing work space. For the covariates, the findings suggested that the average number of first-year enrollment was a significant predictor of doctoral completion rates in non-STEM fields. Non-STEM departments having larger number of faculty with publications, grants, and citations were more likely to have higher doctoral completion rates.

Department Support and Doctoral Time-to-Degree

All programs

Table 3 presented regression results of the relationships between department financial support and academic supports and doctoral median time-to-degree in all programs, STEM, and non-STEM fields. For all programs (Model 4), we found that departments that offered a higher percent of teaching assistantships, fellowships, and providing health insurance were more likely to have longer time-to-degree. None of the academic support variables had statistical significant impacts on doctoral time-to-degree. Our findings indicated that increasing average first-year enrollment and increasing percent of international students were associated with less time-to-degree. Time-to-degree in public institutions was shorter compared with private, not-for-profit institutions. However, increasing the percent of female students was associated with longer average time to doctorate. The relationship between faculty characteristics and doctoral time-to-degree was mixed. Increasing the percent of faculty with grants was statistically significant related to shorter time-to-doctorate. However, faculty citations and the percent of tenured faculty were associated with longer doctoral time-to-degree.

Table 3.

Regressions of Program Factors on Doctoral Time-to-Degree in All Programs, STEM, and Non-STEM Fields.

	All programs			STEM			Non-STEM
	(4)			(5)			(6)
	B	SE	Sig.	B	SE	Sig.	B	SE	Sig.
Program characteristics
Number of students enrolled	0.01	0.00	***	0.00	0.00	***	0.04	0.00	***
Average annual first-year enrollment	−0.02	0.00	***	−0.01	0.00	***	−0.17	0.02	***
Institutional control	−0.22	0.05	***	−0.18	0.05	***	−0.11	0.12
Percent of non-Asian minority students	0.14	0.16		−0.03	0.16		0.05	0.36
Percent of female students	0.41	0.12	***	0.04	0.12		0.23	0.33
Percent of international students	−0.85	0.09	***	−0.60	0.09	***	−0.80	0.23	***
Faculty characteristics
Average number of publications per faculty	0.01	0.01		0.04	0.02		−0.44	0.14	**
Average citations per publication	0.06	0.02	***	0.14	0.02	***	−0.01	0.07
Percent of faculty with grants	−0.92	0.10	***	−0.23	0.14		−0.43	0.24
Awards per faculty member	0.01	0.01		−0.02	0.01		0.08	0.05
Percent of tenured faculty	0.45	0.13	***	0.20	0.13		0.71	0.33	*
Financial support
Percent of students with research assistantships	−0.02	0.04		−0.03	0.08		−0.48	0.28
Percent of students with teaching assistantships	0.27	0.09	**	0.49	0.10	***	−0.23	0.19
Percent of students with fellowships	0.20	0.07	**	0.06	0.07		0.20	0.17
Travel support	0.15	0.17		0.24	0.16		−0.60	0.55
Is health insurance provided	0.20	0.06	**	0.11	0.06	*	0.37	0.13	**
Academic support
Is student work space provided	−0.17	0.05	***	0.04	0.05		−0.22	0.10	*
Training in proposal writing	0.04	0.06		−0.04	0.06		0.17	0.18
Has a graduate student association	0.00	0.12		−0.12	0.11		−0.33	0.33
Training in teaching	−0.11	0.09		−0.10	0.08		0.33	0.32

p < .05. ***p < .001.

STEM fields

For STEM programs (Model 5), increasing the percent of students with teaching assistantships and providing health insurance were positively associated with time-to-degree. Moreover, increasing the percent of international students was more likely to shorten doctoral time-to-degree. However, the STEM departments with faculty who have more publications and citations were more likely to increase time-to-doctorate.

Non-STEM fields

Compared with STEM departments, providing work space was significant in reducing time-to-doctorate for non-STEM departments (Model 6). However, providing health insurance was positively associated with longer time-to-degree. Similar to the STEM fields, the increase of first-year enrollment and international students is associated with shorter time-to-degree in non-STEM programs. Increasing faculty publications was related to shorter time-to-degree. However, increasing the percent of tenured faculty was positively associated with longer time-to-degree.

Discussion

There is very little research about how department factors are associated with doctoral completion across fields in the United States. Using NRC’s American doctorate data, Abedi and Benkin (1987) examined about 400 doctoral programs across 75 disciplines and found that student supports were associated with time-to-degree. Using the same data set, Baird (1990) examined the relationships between program characteristics and doctoral time-to-degree across disciplines, and he found that doctoral time-to-degree varied by fields of study. However, these studies were conducted more than 25 years ago. In this context, this study sought to examine the role of department factors on doctoral completion and time-to-degree using the NRC: 2006 data. Results of this study confirmed that there were influences of departmental support on doctoral completion and time-to-degree.

Previous studies have shown that financial support has significant impact on doctoral retention, and the effect of financial support on doctoral retention varies by types. Students having research assistantships were more likely to complete compared with students with other kinds of financial aid (Ampaw & Jaeger, 2012; Ehrenberg & Mavros, 1995). Consistent with prior studies, we found that departments offering higher percent of research assistantships were more likely to have higher doctoral completion rates and shorter time to doctorate. Departments with higher percent of students with teaching assistantships were more likely to have lower doctoral completion rates and longer time-to-degree. These results were consistent with both STEM fields and non-STEM fields.

We expected that providing academic support would show a positive effect on doctoral completion rate based on the literature. We also assumed that departments that had more student academic support would have higher student academic engagement and completion compared with those departments having fewer student involvement activities. However, we found that none of the student involvement activities were statistically significant after controlling for other variables. While more than 90% of the departments in the NRC: 2006 data set reported providing some kind of academic support for graduate students, the small variations of these academic support variables could be one possible explanation of the insignificant results. Another explanation was that the academic support variables we used only measure whether a department provides such service or not. We did not know about the quality of the academic support and the numbers of students who benefited from these support sources. These were unobserved factors that may influence the academic support estimations in the model. Further research on the role of academic support on doctoral retention at the student level with more precise measurement of academic support is recommended.

Conclusion and Implications

Prior researchers and administrators have called for concerted efforts to provide better experience for doctoral students (Kearns et al., 2007). We have known about a lot of the challenges doctoral students experience from individual and institutional perspectives; however, little is known about how program factors affect doctoral progress across fields at the national level. This study contributed to the literature on doctoral outcomes by examining the role of department factors on doctoral completion and times-to-degree. Understanding what significant program factors effect completion and time-to-degree could provide insights for improving the quality of doctoral programs and increasing doctoral completion rates in American higher education.

Research

This study provided several contributions to research on department factors and doctoral attainment, while also raising new questions. First, this study identified key department factors that related to doctoral program completion and time-to-degree, and these factors differ between STEM and non-STEM fields. Future research needs to go beyond examining the differences between the STEM and non-STEM fields to explore the department differences among each specific field, and how academic support is related to doctoral student retention. Second, research has to assess a broader range of outcomes, such as doctoral student satisfaction, performance, mental health, and socialization. Third, the results of this study were limited to department doctoral completion rate and median time-to-degree for the 2005 to 2006 academic year. Department characteristics and doctoral completion rates may change over time. Further work needs to be done to examine the relationship between department factors and doctoral completion over time. Fourth, although this study contributes to the literature of doctoral retention, it only provided a surface understanding of how the influence of department factors varies by program characteristics. Moreover, we were unable to control all observed and unobserved factors that related to doctoral student retention, progression, and success because of data limitation. Better large-scale and longitudinal data sets of the department factors could help to provide a deeper understanding of the variations among departments. In addition, qualitative studies and quantitative studies should complement each other to better inform practices and to explore the impact of department factors given the full context of departments’ characteristics. Qualitative studies could differentiate department characteristics of each program, examine the nature of doctoral student and department relationships, and reveal the department values and culture guiding program and student behavior.

Theory

Most retention theories have been focused on college students (Berger, 2001; Tinto, 1975). Prior research has found that organizational factors play a significant role in college student retention. In this article, departments were perceived as organizations whose behaviors have important relationships to student retention and graduation (Berger, 2000, 2001). This research extended our knowledge of student retention theories by linking together the organizational behaviors and doctoral student retention. This study confirmed the Girves and Wemmerus’s (1998) graduate student retention framework that program characteristics, faculty characteristics, and financial support were related to doctoral student retention. In addition, findings of this study enhanced our understanding of Berger’s (2001) retention theory by providing evidence of the ways departments could serve as agents of socialization for student persistence. Variations in the program effects by disciplines called for theories that addressing the role of department supports on doctoral students’ outcomes. Further work needs to be done to establish theories that account for the magnitude of impact that department factors have regarding different fields and different types of institutions.

Practice

Finding suggested that program characteristics and faculty characteristics play a much stronger role in doctoral students’ completion and time-to-degree than did the academic support. No overarching relationship was found between academic support (training in writing, training in teaching, and having graduate student association) and doctoral student completion and time-to-degree. However, for doctoral students in non-STEM fields, statistically significant correlations were found between providing work space and increasing completion rate and shorter time-to-degree. Based on these findings, departments should give close attention to what kind of work environments they provided for doctoral students, in particular for non-STEM fields. Developing a supportive working space for doctoral students may be one approach to increase retention.

Examining the relationship between department factors and doctoral completion is important for both academic and administrative perspectives. Findings from this study suggested that department supports influence doctoral completion and time-to-degree differently by disciplines, as Xu (2014) suggested that there were major-based differences in the factors that related to graduate student persistence between STEM and non-STEM fields. In addition, different types of financial support and academic supports had different impacts on doctoral completion and time-to-degree. This was similar to a recent study of Blume-Kohout and Adhikari (2016). They found that different financial support mechanisms in STEM fields had different impact on the enrollment and career choices of doctoral students. Doctoral students with research assistantships were more likely to take research-focused job, compared with doctoral students who were funded by fellowships and traineeship. Findings of this study indicated that there are major-based differences in the influences of financial support and academic support on doctoral completion and time-to-degree. Based on the results, we recommended that doctoral program administrators provide financial and academic supports based on their disciplines and department characteristics.

Footnotes

Declaration of Conflicting Interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

Author Biographies

Enyu Zhou is a PhD candidate in educational leadership and policy analysis at the University of Missouri. Her research focuses on issues of access, affordability and success in higher education.

Hironao Okahana is assistant Vice President, Research and Policy Analysis at the Council of Graduate Schools.

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