Work motivation in Project Management: Are we still interested? A bibliometric analysis of doctoral dissertations

This study included a review and bibliometric analysis of doctoral dissertations on work motivation in project management. Designed to be an exploratory review, work motivation in project-based organizations, and in permanent organizations which undertake projects were considered. 840 doctoral theses from the period 1972-2018 were analyzed. The results showed an increasing number of theses being published on the topic of work motivation, and increasingly on allied topics of leadership, job satisfaction, and project management context. Further, a substantial number of these studies are grounded in phenomenology and grounded theory-adopting interviews as a choice of methodology. Empirical studies were also found to be popular, especially in the early decades. Implications for further studies on the topic of work motivation are presented. Introduction Research in project-human resource management has generated considerable interest in the recent past (Müller & Turner, 2010), some of which focused on understanding work motivation (Sieler, Lent, Pinkowska, Pinazza, 2012; Ayokunle, Xia, Hon, & Darko, 2017). However, the literature may have fallen short in considering the role of context to explain work motivation. The extant literature has focused on investigating work motivation in stable contexts such as a permanent organization (Parker, Broeck, & Holman, 2017) and the theories of work motivation in such stable contexts have been extended to the field of project management. However, modern organizations operate in contexts of high uncertainty (Alotaibi, & Mafimisebi, 2016), and non-traditional working relationships such as a network of actors working with each other for a limited time to achieve specific objectives (Johnson, Creasy, & Fan, 2016). Such organizations are characterized by projects that span across the functional units and being managed as a network, having multiple or divergent objectives and knowledge-based work processes (Lindner, & Wald, 2010); what are known as pluralistic

However, the literature may have fallen short in considering the role of context to explain work motivation. The extant literature has focused on investigating work motivation in stable contexts such as a permanent organization (Parker, Broeck, & Holman, 2017) and the theories of work motivation in such stable contexts have been extended to the field of project management. However, modern organizations operate in contexts of high uncertainty (Alotaibi, & Mafimisebi, 2016), and non-traditional working relationships such as a network of actors working with each other for a limited time to achieve specific objectives (Johnson, Creasy, & Fan, 2016). Such organizations are characterized by projects that span across the functional units and being managed as a network, having multiple or divergent objectives and knowledge-based work processes (Lindner, & Wald, 2010); what are known as pluralistic 6 th International Conference of Modern Approach in Humanities Paris, France November 2 -4 , 2018 contexts (Bredillet,2004). It then becomes important to understand, and establish a theoretical corpus of work motivation specific to such contexts.
Extant research on work motivation shows a growing interest reflected through a number of papers being published on this topic. An analysis of peer reviewed articles from Web of Science database indicates 145 peer reviewed articles. Allied variables such as leadership, job satisfaction, and project team management have been investigated as an outcome of work motivation. Thus, considering such sustained interest in the topic, the larger purpose of this paper is to investigate whether this interest is reflected in the doctoral studies.
Thus, I set out to investigate the following research questions: 1. What are the countries and leading institutions where research on this topic is conducted?
2. What are the trends in methodologies applied to investigate the research problems?
3. What are the most frequently used key words and how are they associated with each other?
The literature on work motivation in temporary organizations, though 'sporadic' in terms of not being able to offer integrative underlying theoretical lenses to explain motivating job An initial search using the key words "motivation" AND "project management" revealed 18,116 documents. The search was further refined by applying the following words as filters based on which the theses are indexed in the database: "work motivation", "motivation", and "project management". 845 documents were then extracted out of which 5 were found not to satisfy one of the above-mentioned criteria-work motivation not being one of the variables that was investigated. Thus, 840 documents were considered for bibliometic analysis. The dates of publication ranged from 1972 to 2018.

Analysis
VosViewer 1.6.8, an open source software tool used for constructing and visualizing bibliometric networks . The key words are extracted from the thesis' abstract and the title.
Words are counted for their presence or absence in the document, what is termed as binary counting. Each word would have to appear for a minimum of ten times to be included in the dataset for analysis. An initial set for 596 terms were first extracted after the first iteration. A relevance score for each of these terms is calculated and 60% of the terms with the highest relevant scores are considered for the initial iteration of the analysis. Thus, 358 terms were considered for the second iteration.

Results
In response to question 1, I found that most of the doctoral dissertations are published in USA (n=761). This is followed by England (n=39), Canada (n=19), and other Asian countries.    Key word association based on the number of times the words occurred in the corpus was run.
It revealed 5 major key words that formed where the other key words gravitated towards each of this one major key word based on the strength of association. Cluster 1-Leader comprised 85 terms of which most significant were-leadership style, incentive, and engineering.
Cluster 2-Interview comprised of 70 terms, most prominent of which were-data collection, multiple case study, interview data, community, and business.
Cluster 3-Job satisfaction comprised of 53 terms, most prominent of which were-climate, tenure, age, burnout, ANOVA, scale, instrument, and hypothesis Cluster 4-Dissertation comprised of 36 terms, most prominent of which were-information system complexity, knowledge management, and case study Cluster 5-faculty comprising of 11 terms, most prominent of which were-higher education, retention, salary, and employment

Response to Research Question 2
For the period between 1972 and 1990, quantitative research methods were predominantly employed over qualitative research methods (c.f. Wagner, 1974;Almohawis,1986;Stewart, 1980) Most common was survey method and ex-post facto empirical research. A limited number of studies applied qualitative research methods-content analysis (c.f. Meell, 1985;Hensler, 1987). A few studies employed mixed research methods-substantiating the results of empirical survey with document analysis, interviews (semi-structured, depth), and case research method. In the ensuing decade between 1990 and 1999 (c.f. Davis, 1995;Wheeler, 1999), similar trends are observed for the preferred choice of research methodology.
However, mixed research methods have gained popularity with techniques such as ethnography and content analysis used in addition to empirical studies. Studies that applied action research methods-quasi-experimental design, personal experience, and computerbased simulations were also used (Cornella, 1992;Tankoonsombut, 1998

Response to RQ 3
The bibliometric analysis of the dissertations based on the strength of association among the key words revealed five major word clusters; three of which pertained to allied variables of work motivation, and two related to methodology. leader's motivation strategies to improve follower performance (Schwartz, 2013), and the influence of leader on virtual team member motivation in new product development projects (Moore, 2007). Furthermore, leadership as a variable is also strongly associated with variables in other clusters such as job satisfaction (Mirza, 2005), and higher education (Evans, 2000).  (Hillerbrand, 2014;Gallaway, 2015), and role business leadership and senior management in motivating the employees (Willis, 2001).
Cluster 3. Dissertation. The third cluster includes terms closely associated with project management and projects. Thus, doctoral studies which focused on motivation among information system professionals (Chiu, 2005;Bowen, 2016), project complexity (Frahm, 2015), project innovation, and team member capability (Tonial, 2009), and knowledge  (Steenkamp, 2014;Evans, 2018). These variables affect motivation by influencing the job attitudes of a person.
Cluster 4. Job satisfaction: This cluster comprises of terms mostly associated with outcomes of work motivation, or control and mediating variables in an empirical model that explains work motivation. Thus, doctoral theses on job satisfaction (Hernick, 2017;Holden, 2002), burnout (Emelander, 2011;Whistler, 2014), and organizational commitment (Chiu, 2005).
Most of the dissertations on these topics have employed quantitative research methods as is evident from the terms -hypothesis, correlation, ANOVA, and scale being in this cluster (c.f. Dunbar, 2002;Tonial, 2009;Moody, 2008).
Cluster 5. Faculty. A significant number of theses have been published in the area of higher education, and on motivation of faculty in higher education institutions. Variables such as employment, salary, loyalty, higher education, and retention aligned closely with each other. Furthermore, the dissertations employed qualitative research methods more commonly over quantitative research methods (c.f.Brown, 2016;Dunbar, 2017;Jaffee, 2015).

Limitations and Strengths
Within the scope of this study, the dissertations were considered from ProQuest Dissertations and Theses Global. Therefore, the dissertations from other databases were not considered.
The study is significant because it focuses on analyzing the content of doctoral dissertations, which is a good indicator of the sustained interest to study work motivation.

Future research
There is an ongoing dialog in the project management literature about the conceptualization of a project. At the heart of this conversation is the concept of 'temporary organizing-a currently held view of a project. Temporary organizing is a 'process' when the actors are temporarily engaged or employed and interact with temporary structures such as tasks or resources. The actors will reflect on the nature of interactions. However, the actors may not completely control the process, and the outcomes of this interaction may lead to some other