The current issue and full text archive of this journal is available at www.emeraldinsight.com/0960-0035.htm Author affiliation in supply chain management and logistics journals: 2008-2010 Michael Maloni Author affiliation in SCML 83 Department of Management & Entrepreneurship, Kennesaw State University, Kennesaw, Georgia, USA Craig R. Carter Arizona State University, Phoenix, Arizona, USA, and Lutz Kaufmann WHU – Otto Beisheim School of Management, Vallendar, Germany Abstract Purpose – The purpose of this study is to extend a series of studies dating back to 1967 that evaluates faculty publication productivity in refereed supply chain management and logistics journals. Design/methodology/approach – Publication output and rankings of academic institutions are based on publication data from six supply chain management and logistics journals from 2008 through 2010. The results are compared to prior studies to identify trends and changes in the rankings. The authors also assess author collaboration influences as well as authorship diversity. Finally, the authors examine further changes to the core set of journals considered for future iterations of this study. Findings – The results indicate that supply chain management and logistics authorship continues to be dynamic. Several schools entered the top 25 ranking for the first time and others substantially improved their rankings. While higher-ranked schools engage in more collaboration within their own institutions, they practice less external and international collaboration. Additionally, the diversity of both individual authors and schools continues to expand, though evidence also suggests some level of emerging stability in sources of authorship. Research limitations/implications – As limitations, the selected journal set may present bias against some authors and institutions, particularly those from outside North America and those choosing to publish in other journals in the field or in related fields. Originality/value – This research stream enables authors and universities to judge their relative productivity of academic scholarship in the supply chain management and logistics field. Moreover, the longitudinal analysis provides insight into the evolving maturity of the field itself. Keywords Citation analysis, Supply chain management, Logistics, Publication productivity, Journals Paper type Research paper 1. Introduction Despite the importance of research outlets such as books, proceedings, and presentations, publications in prominent, refereed journals continue to be the primary criterion for assessing the research productivity of academic institutions. Given this, the authors update and extend a research stream dating back to 1967 that investigates the affiliation of authors publishing in supply chain management and logistics (SCML) journals (Allen and Vellenga, 1987; Carter et al., 2009, 2001, 2005; Gentry et al., 1995; Vellenga et al., 1981). Similar to the earlier studies, the current analysis examines two related research questions: International Journal of Physical Distribution & Logistics Management Vol. 42 No. 1, 2012 pp. 83-100 q Emerald Group Publishing Limited 0960-0035 DOI 10.1108/09600031211202481 IJPDLM 42,1 RQ1. What are the relative contributions of various academic institutions’ authors to SCML journals? RQ2. Which universities’ faculties are most productive based on published articles in these journals? 84 Furthermore, the current study incorporates two additional research questions: RQ3. To what extent does author collaboration influence research productivity? RQ4. What changes have occurred in author concentration since the 1992-2007 time period investigated by Maloni et al. (2009)? These research questions are investigated via an analysis and integration of data from the 2008 through 2010 time period. After describing the methodology in Section 2, we present the relative output of university faculties in Sections 3 and 4, including consideration of the effects of collaboration (Section 5). In Section 6, we extend the work of Maloni et al. (2009) to assess the maturation of the SCML discipline by evaluating author concentration. We then examine the relevance of the current list of journals in Section 7. We conclude with implications in Section 8, focusing on challenges and opportunities for international scholarship. 2. Methodology The scholarly journals encompassed in this investigation focus on the business-oriented managerial and marketing perspectives of SCML rather than engineering, operations research, and urban planning facets. The current examination covers the same six journals from the most recent study (Carter et al., 2009): International Journal of Logistics Management (IJLM), International Journal of Physical Distribution & Logistics Management (IJPDLM), Journal of Business Logistics ( JBL), Journal of Supply Chain Management ( JSCM), Transportation Journal (TJ), and Transportation Research Part E (TRE). It is encouraging to note that all of these journals are now indexed in the Thomson Reuters Web of Knowledge with strong current two-year impact factors: IJPDLM at 2.617, JBL at 3.905, TJ at 2.348, TRE at 1.954, and JSCM at 5.853. The first impact factor for IJLM is expected to be published in 2012. Given that impact factors “will be heavily influenced by which other journals are in the database” (Chapman and Ellinger, 2009, p. 206), the inclusion of these journals is certainly beneficial to the discipline as a whole. Rationale for the omission of other journals (e.g. Transportation Research Record, Journal of the Transportation Research Forum ( JTRF)) is discussed in the original (Vellenga et al., 1981) and subsequent (Carter et al., 2009, 2001) studies. Like the prior study (Carter et al., 2009), a three-year time period (2008-2010) was assessed to allow for more timely research productivity feedback to faculty while still smoothing short-term fluctuations in publication patterns (Phillips et al., 1999). The three-year period has frequently been used in other business disciplines such as accounting (Brown and Gardner, 1985), economics (Pieters and Baumgartner, 2002), marketing (Zinkhan et al., 1992), and operations management (OM) (Vokurka, 1996). Authorship information for each article published in the six journals over the three-year period was amassed in a database. Keeping with the prior study (Carter et al., 2009), publication output was based on authorship share for each paper. Specifically, one point was assigned to an institution in the case of a sole-authored paper; 0.5 points were given to each author’s university for an article with two authors; 0.33 points were credited to each author’s university for an article with three authors, and so forth. Discrete institutional affiliations were assigned for distinct campuses of a university (e.g. Pennsylvania State University vs Penn State Erie). As discussed in prior iterations of this study, the primary limitation of this methodology concerns exclusion of SCML research published in economics, marketing, general management, and OM journals. This could potentially present bias against faculty publishing in prominent outlets in those fields. A similar argument could be made for faculty targeting SCML journals excluded from this study. Still, the established journal set allows a reasonable level of focus to effectively support the main objective of investigating research output in journals generally considered to be core to a large body of SCML scholars. The journal set also allows for a direct comparison to the earlier 2005-2007 time period. 3. Productivity of academic institutions The rankings of the top 25 academic institutions for 2008-2010 (Table I) relative to the six journals generally show significant movement of schools since the previous ranking. The University of Tennessee moved from the fourth to the top ranked position during the 2008-2010 time period. Other ranked schools also increased their positions from the prior period with the University of Maryland moving from tenth to second place, Arizona State University advancing from fifth to third, and the University of North Texas advancing from 19th to fifth. The University of Arkansas, not among the previous study’s top 25, achieved the fourth ranked position. While no non-US universities occupied the top five positions, 11 non-US schools did place in the top 25, including five not ranked in the previous study and three doing so for the first time ever. Overall, ten of the universities in Table I were not ranked among the top 25 schools from the earlier 2005-2007 time period. However, seven of the top ten ranked universities from the current time frame were included among the 2005-2007 top 25. Consistent with the prior study, these findings imply a degree of stability within the top ten positions with greater variability beyond (e.g. the 11th through 25th ranked positions) (Carter et al., 2009). One explanation is that schools with larger, established SCML programs likely retain sizeable faculty bases that are less impacted by the arrival or departure of one or two faculty members. In contrast, faculty turnover at smaller programs will expectedly affect research productivity to a greater extent. As illustration, schools ranking in the top five for 2008-2010 averaged about 16 different authors publishing in the journal set while schools ranked 21-25 averaged half this number. As with the prior study, we examined those schools that have consistently ranked in the top 25 for all eight time periods. Only three universities (the University of Maryland, Arizona State University, and Pennsylvania State University) have repeatedly placed in the top 25 across the 45-year span. This list remains unchanged from the earlier study (Carter et al., 2009). 4. Consistency of rankings across journals Table II provides a deeper analysis of how universities placed among specific journals. The top ranked universities by journal are: IJLM (Cranfield University), IJPDLM (University of Southern Denmark), JBL (The Ohio State University), JSCM (Arizona State University), TJ (University of North Texas), and TRE (National University of Singapore). Author affiliation in SCML 85 Table I. School ranks by sum of author article share for 2008-2010 40 36 30 28 22 26 24 27 26 23 15 17 14 18 16 14 18 12 12 15 10 11 10 16 9 10 8 15.58 12.33 11.93 11.00 10.25 9.42 8.67 8.58 8.37 8.27 6.87 6.73 6.17 6.00 5.68 5.67 5.42 5.33 5.33 5.33 5.08 5.08 5.00 4.83 4.67 4.67 4.67 Author count 25 25 25 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 18 18 21 21 23 24 16 6 11 4 10 5 NR 19 1 NR NR 12 3 NR 8 22 NR 2 17 21 NR NR NR NR NR 22 13 NR NR NR 9 3 2 9 NR 6 22 NR 4 1 22 NR NR NR 8 5 NR NR NR NR NR 20 NR 9 NR NR NR 11 5 2 15 NR 13 NR NR 10 1 NR NR NR NR 6 4 25 NR NR NR NR NR NR 3 NR NR NR NR 1 8 NR NR NR NR NR 13 2 NR NR NR NR NR 5 16 NR NR NR NR NR NR 2 NR NR NR 12 1 13 NR NR NR NR NR NR 8 NR NR NR NR NR 3 7 NR NR NR NR 11 NR 2 NR NR NR 6 5 13 7 NR NR NR NR 23 NR NR NR NR NR NR NR NR NR NR NR NR 10 NR 3 NR NR NR 19 14 4 NR NR NR NR NR 20 NR NR NR NR NR NR NR NR NR NR NR NR 10 NR 4 Rank Rank Rank Rank Rank Rank Rank Rank 2008-2010 2005-2007a 1999-2004b 1992-1998c 1986-1991d 1980-1985e 1974-1979f 1967-1973f Notes: aCarter et al. (2009), bCarter et al. (2005), cCarter et al. (2001), dGentry et al. (1995), eAllen and Vellenga (1987), fVellenga et al. (1981); NR – not ranked in the top 25 during the period of study University of Tennessee University of Maryland Arizona St University University of Arkansas University of North Texas Cranfield University National University of Singapore Auburn University The Ohio St University Michigan St University University of Sydney University of Alabama National Cheng Kung University University of Kentucky Cardiff University Iowa St University University of North Florida University of Southern Denmark University of St Thomas Heriot-Watt University WHU – Otto Beisheim University of California, Berkeley Texas Christian University Pennsylvania State University Chalmers University of Technology Lund University National Chiao Tung University Sum of share 86 School IJPDLM 42,1 40 36 30 28 22 26 24 27 26 23 15 17 14 18 16 14 18 12 12 15 10 11 10 16 9 10 8 5.08 5.00 4.83 4.67 4.67 4.67 Author count (Table I) 15.58 12.33 11.93 11.00 10.25 9.42 8.67 8.58 8.37 8.27 6.87 6.73 6.17 6.00 5.68 5.67 5.42 5.33 5.33 5.33 5.08 Sum of share (Table I) 25 25 25 21 23 24 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 18 18 21 Overall rank (Table I) Note: NR – not ranked (i.e. no publications in the journal during the 2008-2010 time period) University of Tennessee University of Maryland Arizona St University University of Arkansas University of North Texas Cranfield University National University of Singapore Auburn University The Ohio St University Michigan St University University of Sydney University of Alabama National Cheng Kung University University of Kentucky Cardiff University Iowa St University University of North Florida University of Southern Denmark University of St Thomas Heriot-Watt University WHU – Otto Beisheim University of California, Berkeley Texas Christian University Pennsylvania State University Chalmers University of Technology Lund University National Chiao Tung University School NR 33 NR NR 6 17 7 NR 8 3 4 1 NR 9 10 10 NR 30 NR 2 10 NR 17 NR NR 33 NR IJLM rank 3 10 NR NR NR 22 2 18 28 7 12 5 NR 8 65 14 14 9 NR 26 6 12 NR 1 29 4 56 IJPDLM rank NR 56 NR NR 9 15 2 19 16 7 25 35 35 9 1 3 NR 9 NR 35 NR 33 4 NR 35 77 13 JBL rank NR NR 14 NR NR 5 6 9 1 NR NR NR NR 45 44 29 NR NR NR 15 NR 36 NR NR NR NR 3 15 15 NR NR NR NR 87 NR 39 10 4 NR 207 NR 2 166 17 NR NR 1 166 NR NR 3 50 12 NR 49 111 166 NR NR 166 NR 10 4 NR NR 1 NR NR 10 NR 14 NR NR 3 NR NR 10 14 NR 2 NR 25 JSCM rank TRE rank TJ rank Author affiliation in SCML Table II. School ranks by sum of author article share for 2008-2010 by journal IJPDLM 42,1 88 Per Table III, only the University of Tennessee holds a top ten ranking in five journals, and only Auburn University placed in the top ten in four journals. Similarly, just two schools, the University of Arkansas and the University of Maryland, achieved top ten rankings in three journals. These findings are quite comparable to the 2005-2007 study wherein only a handful of schools placed among the top ten in multiple journals (one school in four journals and three schools in three journals). In contrast, a greater number of schools tended to rank in the top ten in multiple journals in earlier editions of the study. As proposed by Carter et al. (2009), this decreasing concentration may result from more universities introducing formalized SCML programs. We explore this idea empirically using the Herfindahl-Hirschman Index (HHI) later in the paper. 5. Author collaboration Autry and Griffis (2005) as well as Cantor et al. (2010) highlight the importance of author collaboration. They establish that collaboration in the field of SCML has been increasing, especially in recent years (Autry and Griffis, 2005), and that collaboration is important to both researcher productivity (Autry and Griffis, 2005) and research impact (Cantor et al., 2010). Specifically, Autry and Griffis (2005) identify a “moderate” level of collaboration in the field. Subsequently, Cantor et al. (2010) find that co-author diversity with respect to different schools, countries, and continents generally leads to higher citations levels received by papers. Seeking further insight into the influence of collaboration on author productivity for the above institutional rankings, we calculated the average number of co-authors working with a particular author within the 2008-2010 time frame at five different levels: (1) Total co-authors. All additional authors collaborating on a paper with the author of study. (2) Internal co-authors. All additional authors from the school of the author of study. (3) External co-authors. All additional authors not from the school of the author of study. (4) International co-authors. All additional authors not from country of the author of study. Top ten ranks School Journals (rank of school in journal) 5 4 3 University of Tennessee Auburn University University of Arkansas University of Maryland Arizona State University Cardiff University Cranfield University Michigan State University National Chiao Tung University The Ohio State University Texas Christian University University of Alabama University of North Texas IJLM (7), IJPDLM (2), JBL (2), JSCM (6), TJ (10) IJLM (9), IJPDLM (8), JBL (9), TJ (10) IJLM (3), IJPDLM (7), JBL (7) JSCM (9), TJ (4), TRE (2) IJLM (8), JSCM (1) IJLM (10), IJPDLM (6) IJLM (1), IJPDLM (5) IJLM (10), JBL (3) TJ (5), TRE (10) IJLM (10), JBL (1) IJLM (6), JBL (9) IJPDLM (9), JBL (9) IJLM (4), TJ (1) 2 Table III. Consistency of school rankings across journals (2008-2010) (5) Trans-continental co-authors. All additional authors not from the continent of the author of study. These levels are not mutually exclusive, and a co-author may qualify for multiple levels. Table IV presents the results for the top 25 schools. To gauge the impact of such collaboration, we calculated correlations between the number of additional co-authors and the sum of author share (i.e. productivity) used to derive the original rankings in Table I. Table V displays the results. For top 25 ranked schools, productivity is significantly positively correlated with total and internal collaboration though the correlations with external and trans-continental collaboration are not significant. Interestingly, international collaboration is significantly negatively correlated with productivity for top 25 schools. These results differ somewhat when considering all schools publishing at least once in the journal set during 2008-2010. Total collaboration retains no significant correlation with productivity for all schools. Internal collaboration is again significantly positively correlated with productivity. However, external, international, and trans-continental collaboration are all significantly negatively correlated with productivity, which is concerning given historical issues with geographically fragmented scholars in the field (Arlbjørn et al., 2006; Gammelgaard, 2001). The signs of these correlation results are consistent when grouping schools by continent, though some differences in significance levels exist. For example, the productivity of North American schools is consistently less negatively correlated with external, international, and trans-continental collaboration than for schools from other continents, suggesting that North American schools are generally more likely to pursue research projects beyond their own institutions. Overall, the idea that higher ranking schools practice more internal collaboration yet less external, international, and trans-continental collaboration than less-productive schools seems counterintuitive. For example, Cantor et al. (2010) demonstrate that cross-school, cross-country, and cross-continental collaboration are increasing and also lead to greater levels of citations received by the papers produced from these collaborations. The timing of the Cantor et al. (2010) data (1987-2007) complements our 2008-2010 data, so the Table V results may signify a recent change in collaboration behavior. Still, intuition would suggest that schools with larger supply chain programs would likely have better research support and contacts to pursue external and international collaboration. On the other hand, such faculty may sense less urgency to collaborate externally given access to multiple internal colleagues with supporting and/or complementary expertise. Moreover, faculty with greater available resources might conduct larger scale research projects that necessitate local (i.e. internal) assistance. Also, such faculty may have better access to well-developed networks of localized companies for research partnerships and data collection. In general, the Table V findings compel a more thorough investigation via future research to validate these conjectures. 6. Author concentration In the previous study, Carter et al. (2009, p. 50) purport that SCML “knowledge is being generated by a more diffuse subset of universities”. With the current top 25 ranking and other evidence (Cantor et al., 2010) indicating dynamic changes since the prior study, we extend the work of Maloni et al. (2009) to further evaluate the maturation of the SCML field by assessing author concentration. Specifically, one would expect that as an academic Author affiliation in SCML 89 Table IV. Author collaboration by school (2008-2010) University of Tennessee University of Maryland Arizona St University University of Arkansas University of North Texas Cranfield University National University of Singapore Auburn University The Ohio St University Michigan St University University of Sydney University of Alabama National Cheng Kung University University of Kentucky Cardiff University Iowa St University University of North Florida University of Southern Denmark University of St Thomas Heriot-Watt University WHU – Otto Beisheim University of California, Berkeley Texas Christian University Pennsylvania State University Chalmers University of Technology Lund University National Chiao Tung University 15.58 12.33 11.93 11.00 10.25 9.42 8.67 8.58 8.37 8.27 6.87 6.73 6.17 6.00 5.68 5.67 5.42 5.33 5.33 5.33 5.08 5.08 5.00 4.83 4.67 4.67 4.67 Sum of share (Table I) 40 36 30 28 22 26 24 27 26 23 15 17 14 18 16 14 18 12 12 15 10 11 10 16 9 10 8 Author count (Table I) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 18 18 21 21 23 24 25 25 25 Overall rank (Table I) 1.85 2.08 2.13 1.64 1.45 2.19 2.00 2.33 2.31 2.17 1.60 1.94 1.36 2.22 2.13 1.79 2.83 1.50 1.50 2.27 1.40 1.64 1.40 2.44 1.11 1.20 1.00 Total 1.05 1.33 1.27 0.86 0.82 1.69 1.42 1.19 0.62 1.13 1.20 0.47 0.86 1.33 1.25 0.57 2.44 1.33 1.17 1.07 0.40 0.73 0.40 1.50 0.67 0.60 0.25 0.80 0.75 0.87 0.79 0.64 0.50 0.58 1.15 1.69 1.04 0.40 1.47 0.50 0.89 0.88 1.21 0.39 0.17 0.33 1.20 1.00 0.91 1.00 0.94 0.44 0.60 0.75 0.08 0.08 0.20 0.00 0.05 0.12 0.50 0.15 0.38 0.04 0.40 0.29 0.21 0.28 0.38 0.29 0.00 0.08 0.00 0.47 0.80 0.27 0.00 0.06 0.44 0.50 0.00 0.08 0.08 0.20 0.00 0.05 0.08 0.13 0.15 0.38 0.04 0.40 0.29 0.21 0.28 0.19 0.21 0.00 0.00 0.00 0.13 0.60 0.18 0.00 0.06 0.00 0.10 0.00 Average number of additional co-authors Internal External International Trans-continental 90 School IJPDLM 42,1 field matures, thought leadership would expand from a core set of pioneering scholars to include additional researchers, causing concentration of authors to decrease. Consequently, author concentration can serve as one measure of the expansion and research diversity of an academic field. Concentration can be quantified by the HHI, which sums the square of the individual market share of each player across the entire market (Maloni et al., 2009). Squaring market share emphasizes large players, so a higher HHI value signifies a more concentrated (i.e. monopolistic or oligopolistic tending) market. Maloni et al. (2009) measured HHIs for five SCML journals (IJLM, IJPDLM, JBL, JSCM, and TJ) from 1992 to 2007, finding higher levels of author concentration (larger HHIs) than traditional business fields such as accounting, finance, marketing, and management. They relate this to the comparatively young age of the SCML field. However, assessing concentration longitudinally across the era via regression analysis, they demonstrate clear trends of decreasing concentration in the field, concluding that author diversity and the field of SCML as a whole have been consistently expanding since 1992. We augment the analysis of Maloni et al. (2009) with author concentration HHIs for the same journal set from the most recent three-year period (2008-2010). We computed four different HHIs with the first being author school affiliation. Maloni et al. (2009) found that author school affiliation concentration was decreasing at a linear rate for the 1992-2007 era (Table VI). We added the 2008-2010 HHI data to their original data set and fit a regression line to the full 1992-2010 data set, again finding a decreasing linear trend with strong significance (measured by R 2) (Figure 1). The same analysis by individual author (Table VI) also reinforces the prior results from Maloni et al. (2009), again finding a significant linear trend when including the 2008-2010 period (Figure 2). With sum of author share Top 25 All schools Asia Australia Europe North America South America Total 27 412 95 8 119 180 10 0.245 * * 20.032 20.061 20.053 20.130 0.000 20.584 * * 0.187 * * 0.302 * * 0.310 * 0.838 * * 0.257 0.362 * * 0.413 * * Trend (1992-2007) Maloni et al. (2009) Author school Author Decreasing – linear Decreasing – linear Author country Author degree school Decreasing – linear Decreasing – non-linear Note: *R 2 significance ( p-value) , 0.001 91 Correlation with number of additional co-authors Internal External International Trans-continental n 0.065 2 0.255 * * 20.268 * * 20.414 * * 20.341 * * 20.263 * 20.658 * * 20.287 * * 20.163 * * 20.144 20.414 * * 20.191 20.108 20.521 * * 2 0.082 2 0.143 * 2 0.155 2 0.414 * * 2 0.165 2 0.087 2 0.521 * * Note: Significant at: *p , 0.01 and * *p , 0.001 Analysis level Author affiliation in SCML Table V. Author collaboration correlations with sum of author share (2008-2010) Trend (1992-2010) Current analysis R 2 ¼ 0.563 * Decreasing – R 2 ¼ 0.622 * Decreasing – Decreasing – R 2 ¼ 0.850 * linear Decreasing – R 2 ¼ 0.848 * linear linear linear nonnon- R 2 ¼ 0.618 * R 2 ¼ 0.738 * R 2 ¼ 0.674 * R 2 ¼ 0.676 * Table VI. Summary of previous and current author concentration analyses IJPDLM 42,1 Figure 1. Concentration of logistics journals by author school – 1992-2010 0.0300 HHI - Author School 92 0.0350 0.0250 R2 = 0.618 0.0200 0.0150 0.0100 0.0050 0.0000 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 0.0120 0.0100 HHI - Author R2 = 0.738 Figure 2. Concentration of logistics journals by author – 1992-2010 0.0080 0.0060 0.0040 0.0020 0.0000 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 Such authorship expansion could partially be a function of the general increasing number of authors per paper (Carter and Ellram, 2003; Miyazaki et al., 1999). Nevertheless, the results still suggest that authors from a greater number of academic programs are contributing to SCML thought leadership and also imply that this growth will not soon subside. This points to sustained expansion of the field to more schools as well as continued changes to future top 25 rankings. To assess global expansion in the current top 25 ranking, we evaluate concentration by author country (based on the school location). The previous study demonstrated a highly significant, linear decreasing trend (Table VI), but the best fit trend line for the 1993-2010 data is now non-linear based on a log transformation (Figure 3), inferring that the international expansion is slowing. So, despite the continued spread of author and school affiliations, the international diffusion of the SCML field may be converging on a core set of countries, at least from the standpoint of the journals of study. This may result from a relative degree of publishing domination by North American and European scholars (Sachan and Datta, 2005; Svensson et al., 2008) as well as the tendency of highly productive schools to collaborate internally as discussed in Section 5. Finally, we examine concentration of author degree school (based on the school granting their highest degree) to assess the rate of expansion or contraction of 0.8000 HHI - Author Country 0.7000 R2 = 0.674 0.6000 Author affiliation in SCML 0.5000 93 0.4000 0.3000 0.2000 Figure 3. Concentration of logistics journals by author country – 1992-2010 0.1000 0.0000 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 institutions generating new scholars. To do so, we split the Maloni et al. (2009) 1992-2007 data into distinct three-year periods (1993-1995, 1996-1998, 1999-2001, 2002-2004, and 2005-2007), omitting 1992. We then collected data from published author biographies for the degree-granting schools of all authors meeting a two-article minimum benchmark (a degree of publishing consistency) within each period, including 2008-2010. Next, we calculated HHIs across these authors for each time period. The results (Figure 4) synchronize with the previous study, again revealing a non-linear (log transformation) pattern. Thus, despite researchers entering SCML from other fields and some growth of doctoral programs, the number of programs generating new researchers seems to be maturing. This is presumably inevitable to an extent given a relatively limited number of schools with sufficient resources to maintain doctoral-level programs. 7. Sensitivity analyses We conclude our analysis by examining the relevance of the six journals used in the present study. We first assess the fit of TRE with the other journals. This was motivated by several factors. First, Table II reveals that many of the highly ranked schools do not publish much or at all in TRE. Second, a highly disproportional number of authors appearing in TRE have faculty appointments in departments that generally reside outside of business schools. Similarly, the primary topics of the TRE articles appear HHI - Author Degree School 0.1200 0.1000 R2 = 0.676 0.0800 0.0600 0.0400 Figure 4. Concentration of logistics journals by author degree school – 1993-2010 0.0200 0.0000 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 IJPDLM 42,1 94 Table VII. Percentage of authors publishing in pairs of journals (2008-2010) to be much less business oriented than the other journals. This is congruent with the prior study (Carter et al., 2009) in which two journals, Journal of Transport Economics and Policy and JTRF, were dropped from the analysis based on similar criteria and findings. To further investigate the fit of TRE with the core journal set, we followed the previous study and analyzed the percentage of authors from departments typically found in business schools (e.g. supply chain management, economics, marketing, information systems, general management, etc.) as opposed to those that generally reside outside of business schools (e.g. engineering and agriculture). About 63.0 percent of TRE authors came from departments typically found in business schools, which does not compare favorably to the range of 92.9 percent (for TJ) to 98.1 percent ( JBL) for the remaining five journals. This suggests exclusion of TRE from the core journal set. As further inquiry into the fit of TRE, we also explored the extent to which scholars are publishing in multiple journals within the set. Conceptually, scholars in a field will tend to target a core set of journals, and highly productive scholars will likely publish in several of these journals. So we would expect overlap of authors across the journals of study if scholars consider these journals to be among a common set of research outlets. Therefore, we evaluated individual pairs of journals (e.g. IJLM and IJPDLM, IJLM and JBL, etc.), counting authors publishing in both of the journals over the 2008-2010 era. Table VII presents these counts as a percentage of all authors publishing in each journal to adjust for significantly different paper counts for each journal. For example, 36.0 percent of authors with at least one paper in IJLM also published in IJPDLM, and conversely, 19.1 percent of authors publishing in IJPDLM also published IJLM. The pairwise overlaps vary from 0.6 to 36.0 percent with IJLM and JBL tending to have the strongest connections with other journals. TRE retains limited overlap, however, providing additional evidence of a lack of fit with the core journal set. We thus performed an updated analysis of the top 25 universities appearing in Table I, without TRE (Table VIII, middle columns). With TRE excluded, five schools exit the top 25 (National University of Singapore, University of Sydney, University of California Berkeley, Lund University, and National Chiao Tung University) and are replaced by four entering schools (University of Oklahoma, East Carolina University, Northeastern University, and University of Nevada). Of these five exiting schools, three (National University of Singapore, University of California Berkeley, and National Chiao Tung University) are largely represented (i.e. . 90 percent) by faculty from outside of the business school, further suggesting a different authorship base for TRE. The above combined findings provide reasonable justification for eliminating TRE in future investigations of the author affiliation studies. Authors publishing in IJLM (%) IJLM IJPDLM JBL JSCM TJ TRE 19.1 24.1 7.5 12.7 1.0 Also publishing in IJPDLM JBL JSCM (%) (%) (%) 36.0 25.9 7.5 19.1 2.0 29.4 16.7 6.7 19.1 1.6 6.6 3.5 4.8 5.5 0.6 TJ (%) TRE (%) Average overlap (%) 10.3 8.2 12.7 5.0 3.7 3.9 4.8 2.5 9.1 16.1 9.7 14.7 8.5 11.8 1.4 2.0 40 36 30 28 22 26 24 27 26 23 15 17 14 18 16 14 18 12 12 15 10 11 10 16 9 10 8 15.58 12.33 11.93 11.00 10.25 9.42 8.67 8.58 8.37 8.27 6.87 6.73 6.17 6.00 5.68 5.67 5.42 5.33 5.33 5.33 5.08 5.08 5.00 4.83 4.67 4.67 4.67 Author count (Table I) 25 25 25 21 23 24 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 18 18 21 Overall rank (Table I) 4.67 3.33 1.67 1.00 5.00 4.58 15.58 6.00 11.60 8.50 10.25 9.42 0.50 8.25 8.37 8.27 2.00 5.73 3.50 6.00 4.60 4.75 5.08 5.33 5.33 5.00 5.08 Sum of share (no TRE) 9 7 4 1 10 15 40 16 29 22 22 26 1 26 26 23 2 15 7 18 13 11 17 12 12 14 10 Author count (no TRE) 19 28 54 79 16 21 1 10 2 5 3 4 145 8 6 7 41 11 24 9 20 18 15 12 13 17 14 Rank (no TRE) 4.67 3.33 0.00 1.00 5.00 3.58 14.25 4.00 11.60 8.50 6.17 9.42 0.50 6.92 8.37 7.27 2.00 5.73 0.00 6.00 4.60 3.42 4.08 5.33 1.50 5.00 4.58 Sum of share (SCML journals) Rank (SCML journals) 1 20 2 4 8 3 131 7 5 6 37 10 224 9 15 22 19 11 52 13 16 70 12 21 14 24 NR Author count (SCML journals) 36 10 29 22 13 26 1 22 26 20 2 15 0 18 13 9 13 12 4 14 9 1 10 12 9 7 0 Notes: SCML journals include IJLM, IJPDLM, JBL, and JSCM; NR – not ranked (i.e. no publications in the journals during the 2008-2010 time period) University of Tennessee University of Maryland Arizona St University University of Arkansas University of North Texas Cranfield University National University of Singapore Auburn University The Ohio St University Michigan St University of Sydney University of Alabama National Cheng Kung University University of Kentucky Cardiff University Iowa St University of North Florida University of Southern Denmark University of St Thomas Heriot-Watt University WHU – Otto Beisheim University of California, Berkeley Texas Christian University Pennsylvania State University Chalmers University of Technology Lund University National Chiao Tung University School Sum of share (Table I) Author affiliation in SCML 95 Table VIII. 2008-2010 rankings without TRE and TJ IJPDLM 42,1 96 The TRE results prompted examination of TJ, the other transportation-centered journal in the set. Both TRE and TJ are indexed in the transportation category of the Web of Knowledge vs the remaining journals indexed in the management category. The evidence does not necessarily suggest removal of TJ, as the journal does have strong average overlap with the other journals (Table VII) as well as a relatively high percentage of authors from traditional business departments (92.9 percent). However, Table II reveals that about half of the top-ranking institutions do not publish in TJ. As such, the last three columns of Table VIII portray re-evaluated rankings without both TRE and TJ. This journal grouping is identified as SCML. Although rankings of several schools do change significantly (e.g. the University of Maryland moving from 2 to 20), the overall results do not differ much from the above analysis when only TRE is excluded. Without TRE and TJ, four of the prior five exiting schools leave the top 25 (National University of Singapore, University of Sydney, University of California Berkeley, and National Chiao Tung University), though National Cheng Kung University and the University of St Thomas also exit. Three of the same four entering schools again reach the top 25 ranking (University of Oklahoma, East Carolina University, and University of Nevada) as do three new entrants (Central Michigan University, the Hanken School of Economics, and the Swiss Federal Institute of Technology). 8. Conclusions The purpose of this paper is to update the historical analysis of the relative contributions of university faculties publishing in a core set of SCML journals. Additionally, we sought to provide insight into the expansion of authorship diversity in the field. The recent (2008-2010) evidence signals that the sources of SCML scholarship are quite dynamic. Specifically, author affiliation rankings (Table I) demonstrate notable changes from the previous study (2005-2007), with several schools achieving significant advances within the top 25 ranking and other schools realizing inaugural entrance to the list. Moreover, diversity of both author school affiliation (Figure 1) and authors (Figure 2), as measured by market concentration, continue to expand at a steady pace. These results imply that the presence of SCML in academic business programs is increasing and that the growth of researchers will not soon subside. This trend supports constructive progress of the field by generating greater breadth of theory and research methods as well as by increasing the quality and reach of educational programs. This expansion also suggests greater competition for publishing in the journals of study, which presumably encourages higher quality scholarship. Such competition may also drive researchers to consider publication outlets in related fields, which will further extend the footprint of SCML. With the journals of study primarily originating in North America, continued global diffusion of authorship remains important given the critical role of SCML to international trade (Hameri and Hintsa, 2009; Hausman et al., 2010). Despite most of the studied journals now maintaining some level of international co- or regional editorship, the review boards still tend to be heavily North American based, certainly not aligning with proportions of world gross domestic product shares. We should note, however, that review boards are becoming more internationally diverse. For example, an examination of the first issues of 2011 of IJLM, IJPDLM, and JSCM reveals that the proportions of non-North American members in the respective review boards are 39.2, 26.5, and 28.3 percent, respectively. Nonetheless, non-North American scholars do face particular hurdles in publishing in the journal set. For example, scholars in many non-North American countries do not have access to such a large, relatively localized set of SCML colleagues as do their North American counterparts. This creates challenges for both finding compatible co-authors and maintaining productive working relationships. Likewise, participation in primary conferences for international scholars often entails trans-continental travel, thus requiring greater time and monetary investment. Additionally, most non-North American authors must overcome language barriers associated with working with authors from other countries and also preparing manuscripts for submission in English. Extant literature suggests that author collaboration in SCML has been expanding from both general (Carter and Ellram, 2003; Miyazaki et al., 1999) and global (Cantor et al., 2010) perspectives. E-mail and emerging low-cost telephone and video conferencing are enhancing supply chain relationships (Golicic et al., 2002) as well as global research. In addition, the education of scholars is converging worldwide. In parts of Europe for example, assistant professors have historically had to independently write an extensive, deeply researched thesis, called habilitation, after successful completion of their doctoral dissertation. During this time, it was largely uncommon to simultaneously publish in journals. Habilitation has since changed in some countries, particularly Germany. Consequently, the respective generation of researchers has gained publication experience much earlier in their careers, hence adding to the productivity of their institutions. As an example, WHU – Otto Beisheim, a German school, entered the latest top 25 ranking for the first time. In general, a large number of non-North American universities (11) place among the top 25 institutions for the 2008-2010 period, which parallels the findings from the prior two studies. As further signs of globalization, 112 of the 618 (18.1 percent) papers (including TRE) involve authors from multiple countries, and authorship of a majority (80 of 112, 71.4 percent) of these papers span multiple continents. Nevertheless, the collaboration results discussed in Section 5 depict research productivity rankings that are negatively correlated with international and trans-continental co-authorship. This presents an opportunity for research-active SCML schools to develop programs that facilitate research projects with international partners, which will enhance the research productivity and globalization of the field. Considering future iterations of this study, the recent and upcoming inclusions of several SCML journals to the Web of Knowledge offer interesting potential enhancements to the analysis. Specifically, we could study the effects on the institutional rankings from weighting journals by impact factors. This could perhaps influence the composition of the core journal set. A similar future research opportunity might include evaluating recent publication quality studies (Ellinger and Chapman, 2011; Gibson and Hanna, 2003; Kumar and Kwon, 2004; Menachof et al., 2009; Zsidisin et al., 2007) in further assessment of the journal set. Additional consideration might also include adding more international-based journals to better globalize the study and minimize North American bias. Candidates might include additional SCML journals currently or soon to be indexed in the Web of Knowledge, such as Supply Chain Management: An International Journal, International Journal of Logistics Research and Applications, and Journal of Purchasing and Supply Management. It may also be worthwhile to evaluate select OM journals (e.g. Journal of Operations Management) to investigate the seemingly diminishing divide between the fields of OM and SCML. In closing, the field of SCML remains relatively new despite advances over recent decades. The analyses described in this paper generally depict an Author affiliation in SCML 97 IJPDLM 42,1 98 evolving discipline. We conjecture that the rankings highlighted throughout the 45 years of this research series will remain highly dynamic based on at least four overlapping drivers currently shaping the field. First, increasing demands from practice are urging schools of business to grow their SCML expertise. Second, as the field expands, further research outlets emerge in the form of new journals as well as greater acceptance of SCML topics in established journals in related disciplines (Hitt, 2011). Third, scholars from other disciplines such as marketing, operations, quantitative methods, and even sociology are recognizing the overlap of SCML to their fields and also appreciating opportunities to reach a greater variety of research outlets for their work (Galaskiewicz, 2011; Lusch, 2011). The previous two points likely combine in terms of integrating new theories into the field of SCML (Sachan and Datta, 2005). Finally, once relatively discrete SCML topics (e.g. transportation, purchasing, warehousing, etc.) are becoming less distinct (Autry and Griffis, 2005; Phillips and Phillips, 1998) as the importance and benefits of integration are recognized (Rutner and Fawcett, 2005). As a whole, all of the above trends depict an evolving and exciting environment for SCML scholars. 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(1992), “Knowledge development and scientific status in consumer-behavior research: a social exchange perspective”, Journal of Consumer Research, Vol. 19 No. 2, pp. 282-91. Zsidisin, G.A., Smith, M.K., McNally, R.C. and Kull, T.J. (2007), “Evaluation criteria development and assessment of purchasing & supply management journals”, Journal of Operations Management, Vol. 25 No. 1, pp. 165-83. About the authors Michael Maloni (PhD, The Ohio State University) is an Associate Professor at Kennesaw State University. His current research interests include sustainability in the supply chain and international trade. He research has appeared in journals such as International Journal of Physical Distribution & Logistics Management, Journal of Business Logistics, Journal of Operations Management, Journal of Supply Chain Management, and Transportation Journal. Craig R. Carter, PhD, is a Professor of Supply Chain Management at Arizona State University’s W.P. Carey School of Business. Dr Carter’s primary research stream focuses on sustainable supply chain management. This research stream encompasses ethical issues in buyer-supplier relationships, environmental supply management, diversity sourcing, perceptions of opportunism surrounding electronic reverse auctions, and the broader, integrative concepts of social responsibility and sustainability. An additional, emerging stream of research considers and analyzes the status and evolution of research in the field of supply chain management, and provides guidance and thought leadership regarding future research directions in the field. His research has been published in the leading supply chain management journals, including Journal Business Logistics, Journal of Supply Chain Management, and Journal of Operations Management. Craig R. Carter is the corresponding author and can be contacted at: crcarter@asu.edu Lutz Kaufmann is a Professor of International Business & Supply Management at WHU – Otto Beisheim School of Management in Vallendar, Germany. He is also an Associate Fellow of Said Business School of Oxford University, UK. His research focuses on supply management and international strategy. He is the European Editor of the Journal of Supply Chain Management. His work has appeared in the Journal of Operations Management, International Journal of Physical Distribution & Logistics Management, Journal of Business Ethics, Journal of International Management, Journal of International Marketing, Management International Review, Journal of Business Logistics, Journal of Supply Chain Management, and The Journal of Purchasing & Supply Management. To purchase reprints of this article please e-mail: reprints@emeraldinsight.com Or visit our web site for further details: www.emeraldinsight.com/reprints