Journal of Operations Management 18 Ž1999. 95–112 www.elsevier.comrlocaterdsw
Discipline note
Operations management research: an update for the 1990s Gertrude P. Pannirselvam a
a,)
, Lisa A. Ferguson
b,1
, Robert C. Ash
c,2
, Sue P. Siferd
d,3
Management Department, School of Business, Southern Illinois UniÕersity at EdwardsÕille, EdwardsÕille, IL 62026-1100, USA b Department of Management and General Business, Hofstra UniÕersity, Hempstead, NY 11549, USA c College of Business and Economics, Department of Business, UniÕersity of Idaho, Moscow, ID 83844-3178, USA d Supply Chain Management Department, College of Business, Arizona State UniÕersity, Tempe, AZ 85287-4706, USA Received 12 June 1996; accepted 23 February 1999
Abstract The issue of operations management ŽOM. research agendas was first advanced in the literature in 1980 with updates and additions in 1981, 1987, and 1989. We believe that the time is ripe for an analysis of the OM research agenda in the decade of the 90’s. In this study, we examine operations management research methodologies and output during the period 1992–1997. Amoako-Gyampah and Meredith wAmoako-Gyampah, K., Meredith, J.R., 1989. Journal of Operations Management 8, 250-262x published a study in which they examined operations management research output from 1982 through 1987. Our objectives are to examine the state of operations management research in the 1990s from the standpoint of topics and methodologies to look for trends, and to determine implications for future research. We assessed the state of research in operations management by examining the research topics addressed and the methodologies used in a subset of seven academic journals that are representative of publications in operations management research. We also surveyed pipeline research in the operations management area by analyzing the topics discussed in national conferences attended by operations management academicians and researchers. Our findings show some significant changes in the kind of research being performed in the 1990s vs. the 1980s. Greater interest in strategy and quality are now apparent in the literature. OM research in the 1990s is also more integrative in nature. We were surprised to find no apparent shift away from modeling solution methods nor any significant shift toward empirical methodologies. q 1999 Elsevier Science B.V. All rights reserved. Keywords: Operations management research; Survey
1. Introduction The increasing importance of operations to business success dictates that operations management ŽOM. research reflect industry concerns. For almost two decades, renowned operations management ) Corresponding author. Tel.: q1-618-650-2732; fax: q1-618650-3979; e-mail:
[email protected] 1 Tel.: q1-516-463-5365; e-mail:
[email protected]. 2 Tel.: q1-208-885-7158; e-mail:
[email protected]. 3 Tel.: q1-480-965-2232; e-mail:
[email protected].
scholars have published research agendas centered on these needs ŽBuffa, 1980; Chase, 1980; Miller and Graham, 1981; Hill et al., 1987; AmoakoGyampah and Meredith, 1989; Meredith et al., 1989.. These scholars have attempted to focus and direct OM research toward areas important and relevant to industry. The primary purposes of our paper are to examine the status of operations management academic research in the 1990s, to compare current research trends with past research directions in terms of topics and methodologies applied, and to discuss implica-
0272-6963r99r$ - see front matter q 1999 Elsevier Science B.V. All rights reserved. PII: S 0 2 7 2 - 6 9 6 3 Ž 9 9 . 0 0 0 0 9 - 1
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tions for future research. For purposes of comparison, we have patterned our study after an earlier one published in the Journal of Operations Management ŽAmoako-Gyampah and Meredith, 1989..
2. Review of relevant literature Buffa Ž1980. called for an operations management research agenda that related to the ‘practical world.’ He recommended that OM researchers make their research results understandable and acceptable to practitioners. Buffa called for continued research in strategic issues such as technology choice, capacity planning, location analysis, and planning and control issues, such as aggregate planning. He also identified positioning, capacity planning, and quality control as important issues to be addressed in service systems. Chase Ž1980. reported on the status of OM research prior to the 1980s. He found that most of the research in the OM area focused on micro-problems and was not integrative. His survey of published OM articles indicated the most popular areas for research were scheduling Ž37%., inventory control Ž22%., and work measurement Ž10%.. Quality control, which focused on statistical issues, was fourth with 6%. Research in service systems dealt almost exclusively with the micro-issue of staff scheduling. Miller and Graham Ž1981. proposed the first comprehensive agenda for operations management research. Unlike the agenda of Buffa Ž1980., Miller and Graham’s agenda was based on opinions drawn from a panel of researchers and practitioners. Miller and Graham called for operations management research in four main areas: operations policy, operations control, service systems, and productivity and technology. To study these issues, Miller and Graham recommended that researchers use case studies and other empirical methods to augment traditional methodologies of simulation and modeling. Hill et al. Ž1987. surveyed dissertations to determine if Miller and Graham’s agenda was being pursued. The scope of their survey included all dissertations in Business Administration and Management with an OM focus completed within the U.S. during the period 1980–1986. Their results indicated that operation control issues such as
scheduling and inventory remained the most popular research areas. However, the greatest increase in the number of dissertations between the two periods of 1980–1982 and 1983–1986 occurred in the areas of process design, strategy, and quality. These three topics were among those emphasized in the Miller and Graham Ž1981. agenda. Process design was suggested for research by Miller and Graham under the productivity and technology area, while strategy and quality were suggested under the operations policy area. Amoako-Gyampah and Meredith Ž1989. surveyed publications in the OM area from 1982–1987. When they classified journal articles in operations management according to Miller and Graham’s agenda, operations control was the most common research topic, accounting for 57% of the articles. Seventy percent of these manuscripts dealt with the still popular issues of inventory control and scheduling. A second area on Miller and Graham’s agenda, productivity and technology, accounted for 21% of the published journal articles, most of which were about process design issues. Interest in process design research showed a substantial increase from the pre-1980s period as reported by Chase Ž1980.. Among the 16% of the articles concerned with operations policy research, the greatest focus was on strategy, with quality addressed to a lesser extent. Only 6% of the articles surveyed dealt with service systems. Amoako-Gyampah and Meredith Ž1989. also surveyed conference proceedings of the Decision Sciences Institute in 1986 and 1987 as a surrogate for pipeline research. Inventory control and scheduling accounted for over 34% of the operations management manuscripts in the proceedings, just as they did in the surveyed journals. However, service systems manuscripts were up from 6% in journals to 14% in the proceedings. Quality and strategy manuscripts in the proceedings showed an increase of about 1% each over the journals. This increased interest in quality and strategy coincided with the findings of the Hill et al. Ž1987. survey of dissertations. Based on the Hill et al. Ž1987. and AmoakoGyampah and Meredith Ž1989. studies, we hypothesized that a current survey of OM related journals would show a higher proportion of manuscripts concerned with process design, strategy, and quality
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than in the pre-1988 period. We also hypothesized, based on the Amoako-Gyampah and Meredith Ž1989. study, that work measurement and facility layout would continue to decline as OM research areas, attesting to a de-emphasis of traditional industrial engineering techniques in the study of operations management. 3. Research methodology 3.1. Journals chosen A major objective of this research was to compare our results with the Amoako-Gyampah and Meredith Ž1989. study. Therefore, we started with the journals covered in their study. We sought to determine if these journals were still being considered high quality journals by OM academicians. Barman et al. Ž1991. published an assessment of relevance and quality of 20 OM related journals, based on opinions gathered from OM academicians on a five point Likert scale. The Barman et al. Ž1991. study confirmed that the six academic journals covered in the Amoako-Gyampah and Meredith Ž1989. study were considered to be among the top 10 OM journals both in terms of relevance and quality. The Journal of Manufacturing and Operations Management, which was included in the Amoako-Gyampah and Meredith Ž1989. study and was among the top 10 journals in the Barman et al. Ž1991. study, is now extinct and hence not included in our study. We added the Production and Operations Management journal to our study since it has, over the past decade, gained some prominence among OM academics as a high quality OM research outlet. Consequently, we report results from these seven journals for all issues for the period 1992 through 1997: Decision Sciences IIE TransactionsŽIIE. International Journal of Operations and Production Management International Journal of Production Research Journal of Operations Management Management Science Production and Operations Management Journal
ŽDS. ŽIJOPM. ŽIJPR. ŽJOM. ŽMS. ŽPOM.
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As Amoako-Gyampah and Meredith Ž1989. did, we surveyed conference proceedings as a surrogate for pipeline research. We surveyed conference proceedings of the Decision Sciences Institute ŽDSI. since it is a peer review conference that is highly regarded by OM academicians. We also surveyed conference program abstracts from the annual meetings of the Production and Operations Management Society ŽPOMS. since it serves as a primary outlet for OM academicians. Both these conferences are well known outlets for OM research presentations and publications. We considered the topics appearing at these conferences to be the best indication of what researchers held as current work-in-process. 3.2. Classification methodology We classified the articles from the selected journals by topic areas and by research methodologies. The topic areas chosen were those used by Chase Ž1980. and by Amoako-Gyampah and Meredith Ž1989.. Use of this classification scheme allows us to compare our results to earlier findings. The journals reviewed for this research publish articles covering a variety of academic subject areas, only one of which is OM. For this reason, a screening process was developed that involved three decisions: 1. Is the article in question an OM article? 2. If so, what OM topic areaŽs. is addressed? 3. And finally, what methodology is used? The first decision required a determination of the central focus of the article. In order to be as consistent and accurate as possible the team of authors initially listed the possible sub-topics that would fall under each of the 17 topic classifications from Chase Ž1980. and Amoako-Gyampah and Meredith Ž1989.. We did this using some of the commonly used OM textbooks. However, doing this did not eliminate all questions about the determination of the OM topic that an article addresses. All the authors conferred when anyone had doubts about the topic of an article until a consensus was reached. As an additional quality and consistency check, we periodically assigned multiple team members to survey a single journal or conference proceeding. Discrepancies were discussed until the team members reached a consen-
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sus. Previous counts sometimes required recounting as agreements were reached. The process detailed in the previous paragraph made categorization of OM focused articles a more straightforward exercise. However, one of the most difficult aspects of this decision process occurred when articles were published by researchers who used an OM topic as an example to demonstrate a new or modified solution technique. We did not consider such articles as meeting the test for a true OM focus. Such solution techniques could have been demonstrated using a finance or marketing problem. Therefore, these articles were not included in our survey. In cases where there were difficulties in determining the true focus of an article, the authors reached consensus before accepting or rejecting that article. For each article, the second decision was to categorize the OM topic area being addressed. One aspect of this decision was to fit the focus of the article into our list of 17 OM categories. While for most articles, this was straightforward; for some articles that addressed relatively new topic areas within OM, such as new product development and
supply chain management, the decision was more of a challenge. Table 1 shows the emerging OM topics and where they were included in this study. Some of the new sub-topics could be included under more than one traditional OM main topic areas depending on the content of the article. Table 1 indicates the original OM topic under which the emerging topics were counted. Table 1 is consistent with the table of keywords that Hill et al. Ž1987. used. Some of the articles surveyed address more than one OM topic. In such cases, we counted each of the topics that were addressed because the objective of this research was to identify the current topics of interest. We also kept track of the type of topics that are studied in combination and the frequency of topic combination occurrences to look for trends in integrative research in OM. The third decision involved determining the solution methodology or methodologies used in each paper. In our initial attempt to survey the articles in our journals, we realized that researchers sometimes use more than one methodology to address their research question. We therefore identified all the single methods and combination methods we found in our survey of the articles.
Table 1 Emerging OM topics areas a 1 2 3 4 5 6 7
8 9 10 11 12 13 14 15 16 17
Emerging OM topics some new product development technology choice
some new product developmnet new product development, technology management, some supply chain management, environmental concerns
some supply chain management
some supply chain management
Original OM topics
4. Published research results
inventory control scheduling
4.1. Topics
process design aggregate planning services quality strategy
capacity planning maintenance purchasing facility layout forecasting project management quality of work life facility location distribution work measurement
We identified 1754 articles in the seven journals for the 1992–1997 period as those with a true OM focus. Of these articles 1565 addressed a single OM topic, 177 addressed two OM topics, 10 addressed 3 OM topics, and one each addressed 4 and 5 OM topics. As a result a total of 1958 OM topics were counted in the 1754 articles. Number of Number of articles topics 1565 1 177 2 10 3 1 4 1 5 Total number of OM topics counted
Total topics counted 1565 354 30 4 5 1958
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Table 2 presents a matrix of operations management research topics by journal. Table 3 shows the combination topics addressed in the 189 combination-topic articles and the frequency of these topic combinations. An examination of Table 2 shows that scheduling Ž25.54%. and inventory control Ž16.19%., accounted for almost 42% of the published research in the journals we surveyed from 1992 through 1997. Quality, process design, and strategy account for 11.34%, 11.29% and 10.88%, respectively. Facility layout accounted for another 7.61%. Below these six topics there was a rapid decline in the volume attributed to a single topic. The other 11 topics comprise the remaining 17.15%. The last three columns in Table 2 also show the percentage of these topics for the periods 1992–1993, 1994–1995, and 1996–1997. Some changes in published OM research topics have occurred between these three time periods. Inventory control and scheduling have not changed in rankings in these three time periods. They still remain at number one and two, respectively. However, the relative frequency of scheduling has steadily decreased during these periods. There has also been a slight drop in the frequency of inventory control as a research topic. The frequency of facility layout as a research topic has dropped steadily over the three periods and its ranking has fallen from 3 in 1992–1993 to 7 in 1996–1997. The relative frequencies of process design, strategy and quality have each increased in the three time periods, except for a slight decrease in the third time period for quality. While the ranking of strategy has been steady through the three periods, process design has gone up in ranking during these time periods. Quality has improved in ranking in 1994–1995 but dropped in ranking in 1996–1997. There are some possible explanations for the continued importance of scheduling today. Even for this mature topic area, there are many new environmental circumstances that keep the subject fresh. These new concerns include an increased focus on time-based competition and flexibility. Attention to customer service, product or service flexibility and time sensitive delivery are important for both manufacturing and service organizations in today’s marketplace. In much the same manner, inventory management is an area of traditional study that is no longer of
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tactical importance only. It assumes strategic importance in terms of new competitive approaches such as work-in-process ŽWIP. inventory cost reductions and finished goods buffer stocks. The development and success of just-in-time methods in Japan have lead to an increased focus on inventory and materials management, and the use of shop floor control techniques as a competitive weapon. Table 3 also shows this shift in scheduling and inventory control toward a more strategic focus vs. the micro-focus noted by Chase Ž1980.. These two topics are now not only studied together but also with other topics such as process design, forecasting, quality, and strategy. All of this may be a consequence of the increased importance of global competition and supply chain management. Amoako-Gyampah and Meredith Ž1989. noted an increase in interest in quality, process design, and strategy in the 1980s. This increase is reflected in their improved frequency among journal articles in the 1990s. Research in quality has taken a more organizational focus in recent years vs. the statistical focus noted by Chase Ž1980.. Process design addresses issues such as technology choices. Research in strategy includes such areas as time-based competition, flexibility, environmental issues, and new product development. Table 3 indicates that these three topics are not only studied together but also in combination with inventory, scheduling, and distribution. This can be explained by the growing interest in supply chain management. 4.2. Research methods Table 4 presents a matrix of research methods by journal. This table provides information about the relative importance of different research methodologies to the field of operations management. The table includes not only the single methods used, but also the methods used in combination. We present the single research methods first and then the multiple methods. Both groups of methods are sorted by the frequency of occurrence. The modeling category in Table 4 includes a number of distinct sub-categories: mathematical programming, calculus, which includes mathematical models with closed-form solutions, and statistical models. This extensive number of sub-categories
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Table 2 Topical classification of operations management research
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G.P. PannirselÕam et al.r Journal of Operations Management 18 (1999) 95–112 Table 3 Topical classification of research addressing multiple topics
Table 3 Žcontinued.
Topic areas
Frequency
%
Inventory control and scheduling Distribution and inventory control Process design and strategy Quality and services Forecasting and inventory control Inventory control and quality Capacity planning and scheduling Inventory control and purchasing Facilities layout and process design Facilities layout and scheduling Process design and scheduling Inventory control and process design Maintenance and scheduling Distribution and scheduling Inventory control and maintenance Process design and quality Quality and strategy Capacity planning and process design Capacity planning and services Forecasting and scheduling Inventory control and facilities layout Process design and services Purchasing and quality Quality and scheduling Aggregate planning and capacity planning Aggregate planning and inventory control Aggregate planning and scheduling Aggregate planning and strategy Capacity planning and inventory control Capacity planning and quality Distribution and purchasing Distribution and services Distribution and strategy Forecasting and project management Forecasting and quality Forecasting and services Facilities location and scheduling Facilities location and services Maintenance and quality Purchasing and strategy Scheduling and services Scheduling and strategy Services and work measurement Services and strategy Capacity planning and inventory control and scheduling Quality and scheduling and strategy Quality and services and strategy Facilities layout and quality and strategy
48 10 10 8 7 6 5 5 5 5 5 4 4 3 3 3 3 2 2 2 2 2 2 2 1
25.40 5.29 5.29 4.23 3.70 3.17 2.65 2.65 2.65 2.65 2.65 2.12 2.12 1.59 1.59 1.59 1.59 1.06 1.06 1.06 1.06 1.06 1.06 1.06 0.53
Inventory control and facilities layout and scheduling Distribution and inventory control and purchasing Capacity planning and distribution and scheduling Process design and quality and strategy Aggregate planning and capacity planning and facilities layout and scheduling Aggregate planning and process design and inventory control and strategy and scheduling
1
0.53
1 1 1
0.53 0.53 0.53
1 1 1 1 1 1 1 1 1 1 1 7 2 2 2 3
0.53 0.53 0.53 0.53 0.53 0.53 0.53 0.53 0.53 0.53 0.53 3.70 1.06 1.06 1.06 1.59
1 1 1
0.53 0.53 0.53
Topic areas
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Frequency
%
1
0.53
1
0.53
1
0.53
1 1
0.53 0.53
1
0.53
189
100.0
helps to explain why modeling is the most highly represented research method with a frequency of occurrence of 41% of the methods applied to operations management research. Simulation is the second most frequently used research method, accounting for about 18% of the methods used. Simulation is often performed to check for validity of the models developed in an article, or to examine the efficiency of heuristics, or to assess model solution times. The combined methodology of simulation and modeling accounts for about 10% of the articles surveyed. Survey methods accounted for about 12% of the articles surveyed. In a few cases survey methods were used in combination with modeling, simulation, and case studies. Theoreticalrconceptual models, which comprise almost 10% of the methods used, include all models that are not of a mathematical nature. These include models that are best represented as some form of chart, graph, flow chart or descriptive models. Survey, case study, field study and laboratory experiment are forms of empirical research. Empirical studies comprise about 18% of the methodologies applied in published research in the field of operations management. Empirical methods were also used in combination with modeling and simulation in about 5% of the articles. Table 4 also shows the percentage of counts in each method separately for 1992–1993, 1994–1995, and 1996–1997. Although modeling and simulation are the most frequently used methods in each of the three periods, their relative frequencies have de-
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Table 4 Methodologies utilized in OM research
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clined. The use of survey methods and theoreticalr conceptual models has increased during the three time periods. This increase, however, is not as high as one might expect based on the agenda recommendations published in previous decades. As Meredith et al. Ž1989. indicated, OM research still remains primarily artificial in nature in the sense that it still involves more modeling than empirical research. 4.3. Topics by method Table 5 presents a matrix of OM topic areas by solution methods. It is not surprising, given the examination of Tables 2 and 4, that the top left-hand corner of this table is so heavily weighted. Modeling and simulation are the most commonly used methods to study scheduling, inventory control, and facility layout. Table 5 also shows that modeling and simulation are applicable to almost all OM topics. Research in quality, especially statistical process control, is most often approached for publication as a modeling problem. The survey method is the second most commonly used method in quality research. This reflects the suggestion made by Meredith et al. Ž1989. concerning the potential use of empirical methods for research in the quality area. Research in process design uses modeling, theoreticalrconceptual models, and survey methods most frequently. Survey is clearly the most popular method for research in strategy followed by theoreticalrconceptual models. Modeling is the most widely used method for research in services. 4.4. Journals profiled An examination of Tables 2 and 4 gives a profile of the OM topics and research methodologies favored by the journals in this review. Table 2 shows that about 55% of the papers surveyed appeared in two journals, IJPR and IJOPM. In terms of breadth of coverage, IJOPM covered all of the 17 topics studied. Fifteen different topics appeared in IJPR, 15 in IIE, 14 in MS, 14 in JOM, 14 in POM, and 13 in DS. IJPR had the highest number of operations management articles. Shop floor control, scheduling and facility layout are the dominant topics of interest in IJPR. However, this journal does publish articles in a wide spectrum of OM topics. IJPR appears to be a
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good outlet for quality and process design manuscripts, as 20% of the journal’s topic coverage is in these two areas. A large number of the articles in IJOPM address the traditional topics of scheduling, inventory control, and process design. However, IJOPM seems to be a good outlet for research in strategy with almost 25% of the total articles in this area. MS, IIE, and DS account for about 14%, 14%, and 6%, respectively, of the topics counted from 1992–1997. Publications in these three journals are heavily concentrated in scheduling and inventory control. IIE has about 18% of its counts in the quality area. JOM accounts for about 7% of the topic counts. JOM seems to favor manuscripts on scheduling and operations strategy, with about 37% of its articles representing these two topic areas. POM accounts for slightly more than 7% of the topics counted in the 6-year time period. A large proportion of its articles is based on research in the scheduling area. However, POM also has a number of articles that are based on research in strategy and quality. Of the journals we reviewed, IJOPM and POM were the only journals in the list to act as significant outlets for OM strategy and quality articles. JOM shows a significant interest in strategy. The relatively high frequency of quality and strategy articles in these journals is a result of some special issues focusing on quality and strategy. However, these special issues reflect the growing need for research in these two areas and the journals’ reaction to this need. Much of the work published in these two areas within these journals is empirical research. As shown in Table 4, IJOPM and POM show the most balance across all the methodology categories found in this study. The publications in these journals reflect their focus on empirical research in the quality and strategy areas of research. The remaining journals emphasize the top two methods of modeling and simulation. Of the seven journals, IJPOM has an interesting profile. Even though there is a clear preference for theoreticalrconceptual work, case studies, and survey research, this journal still places significant emphasis on modeling and simulation. 4.5. Trends in cooperatiÕe research Early in our research process, we found the need to accommodate multiple OM topics being addressed
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Table 5 Matrix of topic areas vs. methodologies
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in the same article. One hundred and eighty-nine articles in this study addressed more than one OM topic. We also observed that research in some of the traditional OM topics such as scheduling and inventory control is becoming more integrative. Research that integrates different OM topics might benefit from the incorporation of multiple viewpoints. Team based research is one way to ensure that multiple viewpoints are included in the research agenda. We classified the journal articles surveyed in this research by the number of authors of an article. Table 6 presents the number of articles that were single authored and multiple authored for each journal we surveyed. The counts are separated into two time periods: 1992–1994 and 1995–1997. As a whole, the percentage of articles that have multiple authors has gone up slightly between the two time periods. This increase is true for six of the seven journals included in the study. POM shows a slight drop in percentage of multiple author articles between the two time periods. This drop, however, is a result of a very slight increase in the number of single author papers, while the number of multiple author papers remains unchanged. The last two rows of Table 6 show the total increase in multiple authored articles.
Table 6 Classification of articles by number of authors Journal
JOM MS IIE DS IJPR IJOPM POM Total
Years
1992–1994 1995–1997 1992–1994 1995–1997 1992–1994 1995–1997 1992–1994 1995–1997 1992–1994 1995–1997 1992–1994 1995–1997 1992–1994 1995–1997 1992–1994 1995–1997
Single
Multiple
Author
Articles
Author
Articles
Total
%
Total
%
12 13 17 23 21 21 13 9 78 47 55 52 12 15 208 180
24.00 21.31 21.79 16.08 21.00 13.13 24.07 21.95 24.22 20.43 29.41 24.64 24.64 24.64 24.53 19.87
38 48 61 120 79 139 41 32 244 183 132 159 45 45 640 726
76.00 78.69 78.21 83.92 79.00 86.88 75.93 78.05 75.78 79.57 70.59 75.36 78.95 75.00 75.47 80.13
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5. Comparison of current journal articles with previous research One of the objectives of examining OM research from 1992 to 1997 was to determine changes in the focus of OM research. Toward this end, we compared the findings from our survey to the pre-1990 research in OM, specifically those reported by Amoako-Gyampah and Meredith Ž1989.. 5.1. Research topic comparisons For statistical comparisons we used only the Amoako-Gyampah and Meredith Ž1989. counts from the academic journals they surveyed, namely MS, DS, IIE, IJPR, JOM, and IJOPM. The AmoakoGyampah and Meredith Ž1989. study classified large project scheduling under scheduling. In our study, we counted project scheduling under project management. In order to enable us to perform statistical comparisons, we moved the eight counts AmoakoGyampah and Meredith Ž1989. had under project scheduling and combined them with their project management counts. Table 7 shows the proportion of research in the 17 topic areas and their rankings from our study and the Amoako-Gyampah and Meredith Ž1989. study of OM research from 1982–1987. The proportions in Table 7 were used to perform a chi-square test to test the hypothesis that the relative proportion of research in the topics in 1992–1997 was the same as in the Amoako-Gyampah and Meredith Ž1989. study. Results of the chi-square test indicate that the difference in the proportions was significant at an alpha level of 0.05. The areas of research contributing most to the difference are distribution, aggregate planning, quality, strategy, facility layout, and process design. The changes in distribution, aggregate planning, quality, and strategy were predicted by the Amoako-Gyampah and Meredith Ž1989. study. There is a considerable increase in the number of articles published in the distribution area. Most research in this area focuses on the effect of distribution systems on lead time and inventory. There is a large decrease in the amount of research published in the aggregate planning area. Aggregate planning has dropped in ranking from 4 to 15 between the two studies. This
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Table 7 Comparison of OM journal topics in the 1980s and 1990s Topics
Inventory control Scheduling Process design Aggregate planning Services Quality Strategy Project management Capacity planning Maintenance Purchasing Facility layout Forecasting Quality of work life Facility location Distribution Work measurement Total
Amoako-Gyampah and Meredith’s study 1982–1987
Current study 1992–1997
Ranking
%
Ranking
%
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17
28.15 16.89 15.23 11.26 6.29 3.97 3.64 3.31 2.98 2.65 1.66 1.66 1.32 0.33 0.33 0.33 0.00 100.00
2 1 4 15 8 3 5 12 9 10 11 6 14 17 13 7 16
16.19 25.54 11.29 0.66 2.71 11.34 10.88 1.74 2.09 2.04 1.99 7.61 1.02 0.20 1.07 3.12 0.51 100.00
decrease reflects the lower proportion of research in this area in the pipeline as indicated by conference papers and doctoral dissertations during the 1980s ŽHill et al., 1987; Amoako-Gyampah and Meredith, 1989.. There are increases in publications in the strategy and quality areas, which has resulted in their improved rankings. The increases in quality and strategy were not only predicted by AmoakoGyampah and Meredith Ž1989., but also by the Hill et al. Ž1987. study. There is a significant increase in the frequency of research in facility layout between these two studies. Research in this area focuses on group technology, cellular manufacturing, FMS, and JIT. However, research in this area has shown a significant decrease in frequency from 1992–1995 to 1996–1997 as indicated in Table 2. There is a decrease in the frequency of research in process design between these two studies. However, research in process design has steadily increased from 1992–1993 to 1996–1997 as indicated in Table 2. Scheduling and inventory control still remain the two most researched topics in OM, but scheduling has surpassed inventory control in popularity. Proportions of publications in facility location, capacity
planning, maintenance, forecasting, and purchasing are relatively similar to those in the 1980s. 5.2. Research methodology comparisons Since we considered all the methodologies used in each article in our survey, while the AmoakoGyampah and Meredith Ž1989. study did not, we did not perform any statistical test to compare the methodologies used in 1982–1987 and 1992–1997. However, an analysis of the relative proportions of the methodologies in the Amoako-Gyampah and Meredith Ž1989. study vs. those in this current study allows us to draw some inferences Žsee Table 8.. Modeling and simulation still remain the most popular methodologies for research in OM. The total proportion of these two methodologies remains virtually unchanged between 1982–1987 and 1992–1997. The overwhelming popularity of these methodologies is not a surprise because OM originated from operations research and management science. This finding is also consistent with the results in the Amoako-Gyampah and Meredith Ž1989. study in which modeling and simulation accounted for 70% of the research surveyed in both journal publications
G.P. PannirselÕam et al.r Journal of Operations Management 18 (1999) 95–112 Table 8 Comparison of past methodology to current methodology Methodology
Amoako-Gyampah and Meredith’s study 1982–1987 Ž%.
Current study 1992–1997 Ž%.
Modeling Simulation Survey Theoreticalr conceptual Case study Field study Laboratory experimentation
38.02 30.80 7.22 14.08
46.89 25.10 11.57 9.57
4.94 3.80 1.14
4.61 1.90 0.35
and pipeline research. Similarly, a survey of methodologies used in OM publications in three popular journals MS, DS, and JOM by Ghosh Ž1994. indicates that the most popular methodology overall is optimization. Empirical research was mostly used to study strategy and productivity issues. In the Amoako-Gyampah and Meredith Ž1989. study the proportion of case study and survey research strategies in pipeline research was almost twice that found in journal publications. One would expect that these methodologies would become more prevalent in current published research. Table 8 indicates a substantial increase in the relative proportion and ranking of the survey method. The expected increase in case study research, however, was not met.
6. Comparison of current journal articles with pipeline research The two previous sections provided a look into the status of current OM research and how it compares to past research. In this section we address what one should expect in future publications in OM research. A study of pipeline research in OM may help us predict what we can expect in future publications. We used conference proceedings of the 1996 and 1997 annual meetings of DSI as an indication of pipeline research. We augmented this data with counts of program abstracts from the annual meetings of POMS for 1996 and 1997. Table 9 presents a survey of conference proceedings and program abstracts in 1996 and 1997. Because it is frequently difficult to discern the method-
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ology from conference proceedings and abstracts, this review covers only the OM topics of the research presented. Table 9 compares the relative frequency of the different OM topics at DSI and POMS in 1996 and 1997 with those in the journals reviewed in this study for 1992–1997. These proportions were used to test the hypothesis that pipeline research in OM has not changed significantly from research published in OM journals. Results of the chi-square test indicate that the difference in the proportions were significant at an alpha level of 0.05. This is true when DSI and POMS conferences are considered separately and also when they are combined. The most significant difference between pipeline research and current journal topics is the higher pipeline interest in quality. While 11% of journal articles address this popular topic, 28% of conference presentations and proceedings cover this topic. This increase in the 1990s is much higher than the increase in the 1980s ŽAmoako-Gyampah and Meredith, 1989.. The relative proportion of pipeline research in services is much higher than the proportion in the journals. This was also true of pipeline research in the AmoakoGyampah and Meredith Ž1989. study. In addition, Table 9 indicates a decrease in the proportion of articles in scheduling, inventory control, process design, and facility layout. In Section 5 we compared the current publication topics to past research publications as represented by the Amoako-Gyampah and Meredith Ž1989. study. The changes in the relative frequencies of OM topics in current research were attributed to the pipeline research interests in 1986–1987. Does this mean that the differences in pipeline research topic interests we found by surveying the conferences in 1996–1997 will result in changes in topical interest in future journal publications? If so, when can we expect these changes to be reflected in the topics of journal articles? The conventional wisdom is that there is a 1 to 3-year time lag from the initial submission of a manuscript until the actual publication of an article. This wisdom is based on the specific data kept by editors and academic journal publishers. We expect that the time lag from initial presentation of a research topic until actual publication might be greater than 3 years due to the additional time from conference presentation to initial journal submission. We
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Table 9 Topical classification of conferences Topic area
DSI 1996–1997 Frequency %
POMS 1996–1997 Frequency %
Conference totals Frequecy %
Journals 1992–1997 Ž%.
Quality Strategy Scheduling Services Inventory control Process design Purchasing Facility layout Distribution Forecasting Facility location Capacity planning Maintenance Project management Aggregate planning Work measurement Quality of work life Totals Total presentations
236 127 100 135 62 58 36 31 16 16 14 10 5 3 4 2 1 856 636
64 33 54 17 23 8 5 3 8 2 1 1 5 4 2 0 0 230 198
300 160 154 152 85 66 41 34 24 18 15 11 10 7 6 2 1 1086 834
11.33 10.82 25.93 2.71 16.18 11.28 1.99 7.61 3.11 1.02 1.07 2.09 2.04 1.43 0.66 0.51 0.20 100.00
27.57 14.84 11.68 15.77 7.24 6.78 4.21 3.62 1.87 1.87 1.64 1.17 0.58 0.35 0.47 0.23 0.12 100.00
hoped to find evidence of the length of that lag in our data. We used the data on the pipeline research during 1992–1993 and journal publications from 1992–1997 to address the questions raised in the previous paragraph. Pipeline research used included the conference proceedings of the DSI and POMS for 1992 and 1993. The relative frequencies of the OM topics in the pipeline research during 1992–1993 and journal publications during 1992–1993, 1994–1995, and 1996–1997 are presented in Table 10. We have classified the 17 OM topics into four categories according to the relationship between conference proceedings during 1992–1993 and journal publications during 1992–1997. The first category of topics includes quality, strategy, purchasing, and maintenance. The conference proceedings percentages, when used as pipeline data, predict that future publication percentages for these topics are expected to rise. Examining the data for journal publications for 1992–1993, 1994–1995 and 1996–1997 shows that those predictions are accurate. We see that the increase in percentage occurs as early as 1994–1995. For example, the actual publications in 1992–1993 for quality represent about 8% of the total, whereas
27.83 14.35 23.48 7.39 10.00 3.48 2.17 1.30 3.48 0.87 0.43 0.43 2.17 1.74 0.87 0.00 0.00 100.00
27.62 14.73 14.18 14.00 7.83 6.08 3.78 3.13 2.21 1.66 1.38 1.01 0.92 0.64 0.55 0.18 0.09 100.00
for the conferences quality represents about 26% of the total. Using conferences as a representation of pipeline publications, we should expect to see an increase in the percentage of publications in quality between 1992–1993 and periods in the future. That prediction clearly shows up as early as 1994–1995 in the journal publication percentages. However, the increase in journal publications is not as high as one would expect. One possible explanation for the low increase might be the existence of other alternate outlets for research in quality, such as Quality Progress, Quality Management Journal, Journal of Quality Management, and the Journal of Quality Technology. For the next category of topics in Table 10, which includes scheduling, inventory control, facility layout, and forecasting, the conference data for 1992– 1993 indicates a decline in interest. Again that prediction is realized in the journal data for the next two journal periods. The data for the three topics, process design, services and distribution that comprise the next category in Table 10 do not support the assumed relationship between conference proceedings and journal publications. In the case of process design, the
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Table 10 Comparison of conference proceedings to journal publications Topics
Conferences
Journals
1992–1993 Ž%.
1992–1993 Ž%.
1994–1995 Ž%.
1996–1997 Ž%.
Quality Strategy Purchasing Maintenance
25.58 12.95 4.37 1.51
7.67 9.41 1.05 1.39
13.14 10.03 2.12 1.98
12.57 13.02 2.66 2.66
Scheduling Inventory control Facility layout Forecasting
16.52 8.58 1.75 0.48
29.44 18.12 10.45 1.22
25.56 14.69 9.46 1.27
22.19 16.12 3.25 0.59
Process design Services Distribution
5.88 10.88 6.99
9.23 2.79 3.83
10.03 3.39 1.69
14.35 1.92 3.99
0.95 1.35 1.59 0.00 0.00 0.64
1.22 1.74 1.05 0.35 0.17 0.87
1.13 2.68 1.27 0.28 0.28 0.99
2.81 1.78 0.89 0.89 0.15 0.15
Project management Capacity planning Facility location Work measurement Quality work life Aggregate planning
pipeline data suggests a decline in interest has occurred. We would expect this decline to be reflected by a decrease in the percentage of journal publications in this topic. We, however, note an increase in journal publications in this area between the periods 1992–1993, 1994–1995, and 1996–1997. Current interest in process design technologies and the importance of time-based competition might explain the increase in journal publications in process design. We conjecture that the DSI and POMS conferences may not always be the best predictors for pipeline research in process design. Researchers in this area may present their initial findings in conferences such as INFORMS or those sponsored by IIE. In the case of services and distribution the expectation would be for a significant increase in publications within these areas. However, no such increase occurs. Instead, for services we see an immediate but only slight increase and then a decrease. For distribution we see an immediate decrease and then an increase; however, the increase only returns the percentage to approximately its 1992–1993 level. Since our expectations for changes in journal publications in services and distribution were not met, the use of conference research as a guide to future research trends may not be perfect. In addition, for these
topics the lag from conference presentations to actual publication may be longer than 4 years. Another explanation for the unmet expectations is the existence of other research outlets in services and distribution such as the Journal of SerÕice Research and the International Journal of Purchasing and Materials Management. For the last six topics in the table in the final category in Table 10 there is little indication of expected growth or decline nor actual growth or decline. This lack of growth or decline is still consistent with using conference research as a surrogate for pipeline research.
7. Discussion and conclusions Our survey of articles published during 1992 to 1997 shows that scheduling and inventory control remain the two most popular topics in OM research. However, it should be noted that at least some of the research in these two areas is more integrative and focuses on emerging topics of practical interest. For example, scheduling research now focuses on timebased competition, just-in-time production control systems, and flexibility. In inventory control, the
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research now integrates the logistics functions. The results from this study also indicate a slow, but steady decline in the publications in these two areas. Process design also continues to be a commonly researched topic within OM. Its ranking has fallen only from 3 to 4 between the 1980s and 1990s. The issues addressed in this topic area in the 1990s are more strategic and include issues such as choice of technology and information technology. Quality and strategy are two topics that have gained popularity among OM researchers in the 1990s. Not only have the relative proportions of research addressing these topics increased, but their ranking among the 17 topics has also increased from 6 to 3 and 7 to 5 for quality and strategy, respectively. Interest in research in quality was not significant until 1994. However, it has steadily increased since then. The increase in proportion for both strategy and quality topics is much less than expected given their increased proportions in pipeline research in the 1980s. Current pipeline research continues to show an increasing amount of research being performed in these two areas. The DSI and POMS conferences are fair indicators for pipeline research for a majority of OM topics. For process design, these two conferences may not be the best indicators of pipeline research. For services and distribution these conferences may be good indicators, however, the journals in our survey are not the only outlets for publication in these two areas of research. In addition it seems reasonable to conclude that the time lag from pipeline research to actual publications varies for different OM topics. The changes in the relative proportion of methodologies used in the research are very limited. The expected change in survey methodology did occur. However, increases expected in the other empirical research method areas were not realized. Empirical methods remain the almost exclusive domain of quality, strategy and services. One would wonder if the length of time lag for acceptance of papers for publication is longer for empirical methods than for traditional techniques such as modeling and simulation. We did not test this hypothesis using our data since we could not identify the methodologies used in conference proceedings and presentations. However, differences in time lag could be one reason
why empirical techniques still lag behind the predictions made in the Amoako-Gyampah and Meredith Ž1989. study. The percentage of research performed by research teams has steadily increased in the 1990s. This increase is most likely a reflection of more integrative research in the OM area. Multiple viewpoints are likely to strengthen the research design and interpretation of results, and thus increase relevance. Preliminary data from this research was presented at a panel discussion at the 1994 Decision Science Institute annual meeting. Jack Meredith Žeditor of JOM. and Lee Krajewski Žeditor of DS., at the annual DSI conference in 1994 ŽSiferd, 1994., noted that there are several reasons that contribute to the slow rate of change in topics found in journal articles over the past decade. One of them is an economic reason. In recent years, the number of positions available for newly graduated PhDs in Operations Management has been fewer than the number of candidates available for the positions. New faculty and candidates for faculty positions are all under tremendous pressure to publish in prestigious journals. Therefore, tried and true topics are more likely to be chosen by emergent researchers because they cannot afford the risks associated with innovative topics or research methodologies. If this is the case, then senior faculty, who are in research mentoring situations, may need to pry themselves away from the more familiar modeling methodologies and move toward empirical techniques. In addition, such mentors could lead the way toward more cross-functional research with colleagues in other colleges who are more familiar with empirical approaches. Such cross-functional efforts may result not only in improved empirical research within the area of OM, but may also result in cross-fertilization of research ideas and agendas. A second reason is that there is some resistance on the part of by editors and especially reviewers to new topics and especially new and unfamiliar solution methodologies. Editors sometimes have trouble finding qualified reviewers for new methodologies. Reviewers may not always feel comfortable with a new method and may discount it due to this lack of understanding. As reviewers become more familiar with new methodologies, this barrier will gradually disappear.
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A third barrier is the high degree of sophistication that new methodologies must exhibit from the beginning in order to be acceptable. Most of the techniques now being introduced to OM are not new to researchers in other social sciences. For example, researchers in the Humanities have much experience with empirical methodologies, and are competent and comfortable with them. OM research that uses a new method cannot start simply and advance through continuous improvement. Such research must be correctly designed and rigorously executed from the beginning. The need for this high level of rigor further complicates the reviewer problem. The reviewers must be able to recognize work properly executed with new methodologies. One way to overcome this barrier is already happening at conferences where tutorials are held in order to educate researchers about new topics and methodologies. These tutorials help would-be authors and reviewers alike to become more competent. The tutorial sessions frequently provide a handout that can be sent by editors to reviewers along with a manuscript concerned with the new methodology. Including a brief tutorial is a gentle way for an editor to help a reviewer with a new topic or methodology without insulting the reviewer. One potential shortcoming with our study is that what is being published may not be representative of what is being submitted to journals. AmoakoGyampah and Meredith Ž1989. also point this out in their study. It is also possible that a journalistic bias may exist that is favorable toward the traditional topics. We investigated these potential discrepancies between what is submitted and what is published in an informal manner. The consensus among a number of journal editors seems to be that neither of these situations is likely to be the case. If a bias exists, it seems more likely that journal editors try to give non-traditional topics a little more exposure. Surveying all the possible journals was not the most efficient way of assessing the trends in OM research. Therefore, we selected a subset of seven journals to include in our survey. Our choice of journals might bias the results towards the topics and methodologies that are favored by these journals. The journals chosen, however, represent outlets that OM academicians prefer to publish their research in
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for prestige and tenure and promotion reasons. The discussion in Section 4.4 highlights the topics and methodologies that appear in each of the seven journals surveyed. This discussion not only allows the readers to identify the biases inherent in each of the journals, but also provides researchers in OM with information to help them decide which journalŽs. to target based on their research topic and methodology used. OM research shows a trend toward more integrative research both within the OM area and also with other business disciplines, such as marketing. Table 3 indicates some of this integrative research within the OM area. This kind of integrative research may require us to be more innovative in the future in our selection of methodologies used to conduct our research. We need to not only adapt methodologies from other disciplines, but also to integrate these methods with the ones traditionally used in OM research. A significant proportion of the current research is easily classified into the topic areas in the classification scheme used in previous studies. We, however, did identify some new and emerging topics that were sometimes difficult to fit within the traditional categories. An area in which much new work is being done today is new product development. A significant portion of this research fits under project management, quality, and strategy. However, during our survey we found that some of the research in this area does not fit accurately under any of the 17 topics chosen. Perhaps it is time to broaden some categories or add others. We recommend adding ‘New Product Development’ as a heading. Environmental issues are being studied more frequently and in greater detail by OM researchers. If this trend continues, we might need to add ‘Environment’ as a new topic for classification purposes. Research in technology management is moving toward a more strategic focus and more often includes the influence of information technology on operations. Classifications of OM research might need to include ‘Technology Management’ as a separate topic. One other new and emerging OM research area is supply chain management. Future assessments of OM research should use an expanded classification of topics to include these new and changing areas in OM research. The use of such an expanded classification of
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OM topic areas in future assessments of OM research will help us clearly identify the strategic and integrative role that OM plays within business practice.
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Chase, R.B., 1980. A classification and evaluation of research in operations management. Journal of Operations Management 1, 9–14. Ghosh, S., 1994. OM research in the 21st century. Decision Line 25, 14–15. Hill, A.V., Scudder, G.D., Haugen, D.L., 1987. Productionroperations management agenda for the ’80s: a progress report. Proceedings of the 1987 Annual Decision Sciences Institute Meeting, Boston, MA. Meredith, J.R., Raturi, A., Amoako-Gyampah, K., Kaplan, B., 1989. Alternative research paradigms in operations management. Journal of Operations Management 8, 297–326. Miller, J.G., Graham, M.B.W., 1981. Productionroperations management: agenda for the ’80s. Decision Sciences 12, 547–571. Siferd, S.P., 1994. The changing management research paradigm: where do quality and operations strategy fit? Proceedings of the 1994 Annual Decision Sciences Institute, Honolulu, HI.
