Identifying Gaps and Contributions of Project-Based Learning in Vocational Education and STEM Fields: A Comprehensive Bibliometric Analysis

This data provides a comprehensive overview of the bibliometric analysis of Project-Based Learning (PBL) in vocational education conducted from 1993 to 2023. The data source comprises 133 various resources, including journals and books, from which 555 documents were considered. The annual growth rate of these publications stands at 6.44%, indicating a consistent increase in the volume of literature on this subject over the 30-year period. The average age of a document within this dataset is 7.31 years, and the average number of citations per document is 17.96. This latter figure suggests a substantial level of scholarly engagement with these works, underscoring their relevance and influence in the field. A total of 18,175 references were found within the documents collected. In terms of document contents, 2,544 “Keywords Plus” and 1,302 “Author’s Keywords” were identified. These terms provide insight into the recurring and central themes explored in literature. Regarding authorship, 1,636 different authors contributed to the corpus of documents, with 73 authors producing single-authored documents. The degree of collaboration is further reflected by the fact that the average number of co-authors per document is 3.27. The data also reveals a significant degree of international collaboration, with 17.3% of the documents having international co-authorship. This focus on articles signifies a preference for the depth and rigor typically associated with this type of scholarly output in the analysis. The main information about data is listed in Table 2.

The dataset shown in Figure 2 depicts the annual progression of published articles on Project-Based Learning (PBL) in vocational education from 1993 to 2023. From 1993 to 2002, the field saw minimal activity, with no more than 3 articles published per year. This suggests that PBL in vocational education was not a widely researched topic during this period. A significant increase in the number of articles occurred in 2003, with 13 articles published that year. The level of publication activity remained relatively stable through 2007, with a slight dip in 2007. From 2008 onward, the field began to witness a steady rise in publication frequency. This upward trend indicates a growing interest and recognition of PBL in vocational education among scholars. A more considerable surge is observed from 2014 onward, with the number of annual publications frequently surpassing 30. In 2017, the number of articles jumped to 45, representing a substantial increase in research output compared to previous years. The growth continued, reaching its peak in 2022 with 58 articles published that year. The year 2023, although not yet complete at the time of data collection, already had 13 articles, suggesting the field’s continued dynamism. Overall, the data signifies a growth trend in PBL in vocational education research, highlighting its rising importance as a research area. The increasing number of publications also suggests that PBL in vocational education has been receiving escalating scholarly attention and validation, implying its recognized value in enhancing vocational education outcomes.

Figure 2:
Annual production of articles from 1984 to 2023.

The top 10 journals in terms of the number of publications are listed in Table 3.

The “International Journal of Engineering Education” leads the pack, having published 99 articles on the topic. This suggests that the integration of PBL in vocational education is a major focus in the realm of engineering education. The “European Journal of Engineering Education” is the second most prolific, contributing 73 articles. This indicates significant interest and ongoing research in PBL within the context of European vocational engineering education. “IEEE Transactions on Education” ranks third with 63 articles. As IEEE is a renowned international professional organization dedicated to the advancement of technology, this journal’s active engagement with PBL in vocational education underlines the perceived importance of this teaching methodology in technological and engineering disciplines. “Journal of Engineering Education Transformations” and “Computer Applications in Engineering Education” have also significantly contributed to the body of knowledge with 20 and 19 articles, respectively, highlighting the relevance of PBL to these specific aspects of engineering education. The “International Journal of Electrical Engineering and Education”, “Advances in Engineering Education”, and “Journal of Professional Issues in Engineering Education and Practice” each have published between 11 and 15 articles on PBL in vocational education, further illustrating the topic’s relevance across various engineering disciplines. International Journal of Technology and Design Education, with 10 articles, highlights the application and efficacy of PBL in the spheres of technology and design education. The data reflects a strong interest in PBL within the field of engineering education, underlining the method’s potential for enhancing learning outcomes in vocational and technical education settings.

The distribution of authors productivity concerning the frequency of published articles on Project-Based Learning (PBL) in vocational education has been analyzed using Lotka’s Law. This law postulates that the number of authors making contributions is about 1/n² of those making one contribution. According to the data observed, the bulk of the contributions (92.7%) come from authors who have written a single document, indicating a large pool of individual contributors to the field. This aligns with Lotka’s Law, which predicts that most authors will contribute only once. In this context, authors who have contributed twice to the corpus make up 5.4% of the total authorship, those who have contributed three times make up 1.2%, and those who have made four contributions are 0.4%. The number continues to decrease with the rise in the number of contributions, with one author having written five documents and three authors having written seven documents, each representing 0.1% and 0.2% of total authorship respectively. Notably, one author has contributed twelve times, a significant outlier in the distribution. Overall, the distribution generally aligns with Lotka’s Law, demonstrating that in the field of PBL in vocational education, there are many authors who contribute once or twice, and fewer authors who contribute more frequently. The data shown in Table 4 and Figure 3 presents a geographical analysis of the scientific production rate and the distribution of publication frequency across different countries provides a valuable perspective on global engagement with this field of study. The United States leads the scientific production, contributing 371 articles to the corpus of PBL literature, indicating a high degree of interest and research activity in this field within the country. Spain, the second-most productive country, has contributed 297 articles, exhibiting substantial research efforts in this domain in the European context. China, with 124 articles, ranks third, showing significant interest in PBL within the Asian academic landscape. Portugal and Australia are also noteworthy contributors, with 85 and 77 articles respectively, reflecting their active research environments around PBL in vocational education. Denmark and India have each con- tributed 69 articles, showcasing their engagements with PBL. Meanwhile, Malaysia and the United Kingdom each produced 67 articles, demonstrating their commitment to exploring and enhancing PBL in vocational settings. Lastly, Brazil, with 60 articles, contributes to the research corpus from a South American perspective. Overall, the data underscores a global interest in PBL in vocational education, with the United States and Spain leading in terms of research output, followed by a range of countries from different regions worldwide.

Figure 3:
Plot of Scientific production based on country.

The citation analysis conducted in the study highlights the five most influential papers as shown in Table 5. The most cited paper, authored by De Graaf et al.^[30] titled “Characteristics of problem-based learning”, has accrued 579 citations, reflecting its profound influence on the understanding of problem-based learning methodologies. Another seminal work is “Implementing the Project-Based Learning approach in an academic engineering course” by Frank M et al.^[31] which has garnered 296 citations, highlighting its practical application in engineering education. The third influential paper, “Problem-Oriented and Project-Based Learning (POPBL) as an innovative learning strategy for sustainable development in engineering education” by M. Lehmann et al.^[32] has 272 citations, demonstrating its impact in introducing sustainable pedagogical strategies. Tseng et al.^[33] work “Attitudes towards Science, Technology, Engineering and Mathematics (STEM) in a Project-Based Learning (PBL) environment” has received 235 citations, indicating its importance in shaping attitudes towards STEM education. Lastly, “PBL and CDIO: complementary models for engineering education development” by Kristina Edstrom.^[34] has amassed 180 citations, emphasizing the synergies between two effective pedagogical models, PBL and Conceive-Design-Implement-Operate (CDIO), for enriching engineering education.

This segment delves into the prominent themes in the research on Project-Based Learning (PBL) in vocational education and their evolution over time by examining the keywords and thematic progression. An analysis of keyword co-occurrence serves as an effective method for representing the structure of scholarly knowledge, pinpointing hot topics, and identifying patterns within a specialized domain. The extraction, mapping, and clustering of terms from keywords allows for the clear demarcation of research themes. As depicted in Figure 4, the map consists of circles and lines with each circle acting as a node that corresponds to an author’s keyword. The size of the circle is indicative of the frequency of occurrence-larger circles represent keywords that appear more often in the literature. The connecting line between two nodes signifies the degree of relationship between two keywords. The line’s thickness demonstrates the frequency of keyword co-occurrence, while the distance between two nodes represents the strength of topic similarity. Each circle’s color corresponds to the specific cluster of the keyword to which the node belongs. For this section of the study, the co-occurrence of author keywords served as the analytical unit to examine the research themes in PBL. A minimum co-occurrence threshold was set at four, after which the co-occurrence of a total of 69 author keywords were visualized and subsequently divided into distinct categories. Cluster 1 aggregates a set of keywords that encapsulate the concepts of “project-based learning”, “engineering education”, “experiential learning”, “education”, “curriculum”, “skills”, and “STEM”. This cluster demonstrates a significant thematic emphasis on the integration of project-based and experiential learning methods within the curriculum of engineering and STEM education, with a particular focus on skill development.

Figure 4:
Co-occurrence network of author keywords.

To illustrate the evolution of Project-Based Learning (PBL), a thematic evolution analysis was performed. The analysis used Callon centrality (theme importance) and Callon density (theme development) to categorize themes into four typologies as shown in Figure 5. Themes in the upper-right quadrant are significant and well-developed, while those in the lower-right quadrant are important but focus on specific cross- cutting topics. Themes in the lower-left quadrant are marginal and less developed, while those in the upper-left quadrant, though less important, are well-developed in a specific domain. Design thinking, challenge-based education, and multidisciplinary education are the emerging themes. These contemporary themes underline the evolving nature of project-based learning, emphasizing innovative problem-solving approaches, an increased focus on real-world issues, and the intersection of various fields of study. The prominence of these topics suggests a shift towards more holistic, interdisciplinary, and application-based learning approaches in educational research and practice.

Figure 5:
A thematic evolution analysis of Project-Based Learning (PBL).

The discussion section of this bibliometric analysis illuminates the burgeoning interest and substantive evolution in the research landscape of Project-Based Learning (PBL) within vocational education, spotlighting an annual growth rate of publications at 6.44% over three decades. This trend not only signifies the escalating scholarly engagement with PBL but also mirrors the shifting pedagogical paradigms in response to the evolving demands of the global labor market. The analysis delineates a movement from traditional, didactic teaching methods towards more innovative, student-centered pedagogical frameworks like design thinking, challenge-based education, and interdisciplinary learning. Such methodologies emphasize active engagement, critical thinking, collaboration, and real-world problem-solving, skills deemed essential for the contemporary workforce. The shift toward Project-Based Learning (PBL) in vocational education represents a significant pedagogical evolution, deeply rooted in several influential educational theories that emphasize active, engaged, and contextual learning. This paradigmatic transition is not just a trend but a response to the changing demands of the global workforce and the need for education systems to produce graduates who are not only knowledgeable but also adept in critical 21st-century skills such as problem-solving, collaboration, and adaptability.

At the heart of this pedagogical shift is the Constructivist Learning Theory,^[35] which asserts that learners construct knowledge through experiences and reflections on those experiences. This theory lays the foundation for PBL by advocating that learning is most impactful when students are actively involved in meaningful tasks that require them to navigate and solve real-world problems. PBL, with its emphasis on engaging students in projects that simulate real-life challenges, aligns perfectly with this constructivist approach, ensuring that learning transcends the acquisition of theoretical knowledge to include the development of practical skills and critical thinking abilities. Complementing the constructivist perspective is the Theory of Situated Cognition,^[36] which posits that knowledge and learning are intricately linked to the context in which they occur. This theory reinforces the value of PBL in vocational education, where the seamless integration of theoretical knowledge and practical application is crucial. By sitting within authentic contexts, PBL not only enhances comprehension and retention but also better prepares students for the complexities and nuances of workplace environments. The experiential nature of PBL ensures that students gain hands-on experience, fostering a deeper understanding of subject matter and enhancing their ability to apply knowledge in practical settings. Furthermore, the 21st Century Skills framework underscores the imperative for education systems to cultivate skills such as creativity, critical thinking, collaboration, and communication. PBL caters to this need by incorporating interdisciplinary projects and teamwork into the curriculum, thereby creating a learning environment that encourages the development of these essential competencies. This approach prepares students to thrive in a dynamic and interconnected world, where the ability to navigate complex problems and work collaboratively across disciplines is paramount. The Theory of Interdisciplinary Integration^[37] highlights the necessity of bridging diverse fields of knowledge to tackle today’s multifaceted challenges. The increasing adoption of multidisciplinary approaches within PBL in vocational education, as evidenced by our analysis, illustrates the practical application of this theory. It signifies a move towards educational experiences that transcend traditional disciplinary boundaries, thereby equipping students with a versatile and comprehensive skill set that is adaptable to various contexts and challenges.

The bibliometric analysis conducted in this study reveals not only the quantitative growth of PBL research in vocational education but also qualitative shifts towards more innovative and integrated pedagogical models. This global trend is reflective of an educational paradigm shift towards methods that are more aligned with the demands of the modern workplace, which values problem-solving, adaptability, and interdisciplinary collaboration. Countries leading in PBL research, such as the United States and Spain, have shown a significant commitment to developing and implementing PBL strategies within their vocational education systems. This commitment suggests a recognition of the value of PBL in enhancing educational outcomes and preparing students for the workforce. The international collaboration patterns identified in our analysis further highlight the importance of cross-border educational initiatives in sharing best practices and fostering innovation in vocational education strategies. The thematic evolution of PBL research indicates a growing interest in integrating innovative pedagogical frameworks like design thinking and challenge-based education. These frameworks resonate with the theoretical underpinnings of PBL, emphasizing the importance of engaging learners in problem-solving and creative thinking processes. The focus on interdisciplinary and multidisciplinary approaches further underscores the recognition of the complex nature of real-world problems, which often require solutions that draw upon diverse fields of knowledge. The expanding body of research on PBL in vocational education, as evidenced by our bibliometric analysis, underscores a significant pedagogical shift towards more engaged, experiential, and context-based learning environments. This shift, grounded in solid educational theories and aligned with global educational trends, points towards an evolving educational paradigm. One that not only addresses the immediate skills needs of the labor market but also prepares students to navigate the complexities of a rapidly changing world. As such, the insights derived from this analysis serve as a valuable resource for educators, policymakers, and researchers, guiding the future development of vocational education to better meet the demands of the 21st-century workforce.

The insights gleaned from this analysis bear significant implications for educators, policymakers, and curriculum developers. For educators, the findings underscore the importance of embracing PBL and related methodologies to create more engaging, relevant, and effective learning experiences. Curriculum developers are called upon to integrate these pedagogical models into vocational education programs, ensuring that students not only acquire technical skills but also develop the soft skills necessary for the modern workplace. For policymakers, the international collaboration pattern highlights the potential for cross-border initiatives in vocational education. Sharing best practices and resources can facilitate a more unified and effective approach to incorporating PBL across different educational systems and cultural contexts. While this analysis provides a comprehensive overview of PBL in vocational education, it also illuminates areas for future research. The reliance on English-language, Scopus-indexed documents suggests the potential for language and database biases, indicating a need for broader, more inclusive research methodologies that encompass diverse languages and sources. Furthermore, the analysis highlights the lack of longitudinal studies on the long-term impacts of PBL on vocational outcomes. Future research should aim to fill this gap, providing evidence of PBL’s efficacy over time and across various contexts. Such studies could significantly contribute to the validation and optimization of PBL as a pedagogical approach in vocational education. Additionally, the evolving thematic focus of PBL research suggests emerging areas of inquiry, including the integration of digital technologies and the adaptation of PBL methodologies to online and blended learning environments. Exploring these dimensions could offer valuable insights into the scalability and flexibility of PBL, ensuring its relevance in an increasingly digitalized educational landscape. In summary, this bibliometric analysis has painted a comprehensive picture of the trajectory and thematic evolution of PBL research in vocational education. It has underscored the growing scholarly interest in PBL, reflecting a broader shift towards more engaging, relevant, and effective.

The analysis of Project-Based Learning (PBL) in vocational education reveals significant disparities in its adoption and effectiveness across different countries, which are closely tied to the varying degrees of industry association with learning. These gaps present both challenges and opportunities for countries that are lagging in implementing PBL effectively. A closer examination of these disparities offers insightful lessons and potential strategies for enhancing vocational education systems worldwide. Countries leading in PBL implementation, such as the United States and Spain, often showcase strong partnerships between educational institutions and industries. These collaborations facilitate real-world learning experiences, ensuring that the curriculum is directly aligned with current industry needs and future job market trends. In these settings, PBL is not just a pedagogical strategy but a bridge that connects classroom learning with practical, on-the-job experiences. Such integration is crucial in vocational education, where the primary goal is to equip students with the skills and knowledge that are immediately applicable in the workforce. The success of PBL in these contexts is largely attributable to the active involvement of industry stakeholders in curriculum design, project creation, and even evaluation processes, ensuring that students engage in learning activities that mirror real-world challenges and requirements. In contrast, countries that are less effective in harnessing the potential of PBL often face challenges such as limited industry engagement, lack of resources, and insufficient teacher training in PBL methodologies. These challenges hinder the ability of educational institutions to provide students with meaningful project-based experiences that are closely tied to industry needs. Without the active participation of industry partners, PBL initiatives may fail to capture the dynamic nature of the labor market, rendering the learning experience less relevant and impactful for students’ career trajectories. Furthermore, the absence of a supportive policy framework and adequate funding can exacerbate these issues, limiting the scope and quality of PBL implementation. The disparities in PBL effectiveness highlight a critical need for countries lagging to learn from the experiences of their more successful counterparts. For instance, establishing stronger connections between vocational schools and local industries can create more opportunities for students to engage in projects that are directly relevant to their future careers. Such partnerships can also facilitate knowledge exchange, whereby educators can gain insights into emerging industry trends and skills requirements, while industry professionals can contribute to curriculum development and provide mentorship to students. Moreover, investing in teacher training is essential to ensure that educators are equipped with the skills and knowledge to design and facilitate effective PBL experiences. Professional development programs that focus on PBL methodologies can empower teachers to create engaging, real-world projects and assess student learning in meaningful ways. Additionally, policy initiatives that promote industry involvement in vocational education and provide financial support for PBL initiatives can create a more conducive environment for the adoption and scaling of PBL strategies. In summary, the gaps between countries in the effectiveness of PBL implementation offer valuable lessons for those looking to enhance their vocational education systems. By fostering closer industry-education partnerships, investing in teacher training, and supporting policy and funding mechanisms that promote PBL, lagging countries can bridge the gap and leverage PBL as a powerful tool for preparing students for success in the modern workforce. This approach not only benefits individual learners but also contributes to the broader economic and societal development by ensuring a skilled, adaptable, and future-ready workforce.

While this bibliometric analysis provides a comprehensive exploration of the trajectory and impact of Project-Based Learning (PBL) in vocational education, particularly emphasizing its contributions to STEM fields and its role in addressing educational and career-related challenges, it is essential to acknowledge the study’s limitations for a balanced assessment of the findings. These limitations not only offer scope for critical reflection but also pave the way for future research directions that can further enrich our understanding of PBL’s potential and application. Firstly, the study’s reliance on Scopus-indexed documents in English introduces a language bias, potentially overlooking significant research published in other languages or within less accessible databases. This limitation could mean that the analysis may not fully capture the global scope of PBL research, especially contributions from non-English speaking regions where PBL might be implemented in unique and contextually relevant ways. As educational paradigms and pedagogical innovations vary widely across different cultural and educational systems, a more inclusive research methodology that encompasses a broader linguistic and geographic spectrum could reveal additional insights and diversify our understanding of PBL’s global impact. Moreover, the bibliometric methodology, while powerful for mapping trends, authorship, and citation networks, may not fully capture the qualitative nuances of research quality or the practical impact of PBL implementations.

Bibliometric analysis excels in highlighting the most cited and potentially influential papers, but citation counts alone do not always equate to practical relevance or pedagogical effectiveness. Consequently, there’s a need for complementary research approaches, such as meta-analyses or qualitative case studies, that can delve deeper into the pedagogical contexts, learner experiences, and long-term impacts of PBL on vocational outcomes. Another significant limitation is the study’s snapshot nature, which, despite covering three decades of research, may not adequately address the dynamic and evolving nature of PBL and its application in vocational education. The pace of technological advancement and the shifting demands of the labor market require continuous adaptation and innovation in educational strategies. As such, the study’s findings, while indicative of trends up to 2023, may not fully anticipate future developments in PBL pedagogy, emerging technological tools that could enhance PBL implementation, or evolving skills demands of the workforce. The study also identifies a gap in longitudinal research on the long-term effects of PBL on students’ career trajectories and job performance, pointing to a need for future studies that track vocational outcomes over time. This limitation underscores the challenge of measuring the sustained impact of educational interventions in a rapidly changing world. Longitudinal studies, potentially incorporating mixed methods to combine quantitative outcomes with qualitative insights, could offer a more comprehensive understanding of how PBL influences career readiness and success.

Furthermore, the analysis suggests a paucity of comparative studies assessing the efficacy of PBL against other pedagogical approaches within vocational education. This gap highlights an opportunity for future research to systematically evaluate PBL’s effectiveness, providing educators and policymakers with evidence-based guidance on the most impactful teaching and learning strategies for vocational training. Additionally, the thematic analysis, while uncovering emerging trends and areas of focus within PBL research, may not fully account for the practical challenges of implementing PBL in diverse educational settings. Factors such as institutional support, teacher training, resource availability, and curriculum alignment play critical roles in the successful adoption of PBL. Research that specifically addresses these implementation challenges, particularly in resource-constrained environments, could provide valuable insights for practitioners looking to adopt or adapt PBL methodologies. While this bibliometric analysis sheds light on the significant growth and thematic evolution of PBL research in vocational education, acknowledging its limitations invites a more nuanced understanding and encourages further exploration. Future research that addresses these limitations can enhance our comprehension of PBL’s effectiveness, inform practice and policy, and ultimately contribute to the development of a robust, skill-oriented education system that aligns with the needs of students and the global labour market.

The findings of this comprehensive bibliometric analysis spotlight significant insights into the evolution, contributions, and persisting gaps within the realm of Project-Based Learning (PBL) in Vocational Education and STEM fields. These insights not only illuminate the pathway for academic inquiry but also delineate actionable strategies for policymakers and educational practitioners. Herein, we propose recommendations aimed at leveraging the strengths and addressing the limitations of PBL, focusing on innovative teaching methods and competency indicators as vital components for enhancing vocational and STEM education.