Guest editorial: Synthesizing knowledge in service research: an introduction to the special issue on meta-analyses and systematic reviews

The field of service research has grown substantially over the past several decades, generating a rich and diverse body of empirical studies that examine the drivers of service quality, customer experience and firm performance. As this literature continues to expand, however, so does the challenge of interpreting findings that are often fragmented, context-specific or at times contradictory. Synthesizing this growing body of knowledge in a rigorous and systematic manner has therefore become one of the most pressing needs in service theory and practice.

It is against this backdrop that this special issue of the Journal of Service Theory and Practice was conceived. This issue, titled Advancing the Understanding of Service Theory and Practice: Meta-Analysis and Systematic Review, brings together nine papers that employ rigorous quantitative and qualitative synthesis methods to consolidate, analyze and advance our understanding of key issues in service research. By prioritizing synthesis over single-study empiricism, this special issue responds to growing calls in the marketing and service disciplines for more robust, generalizable and evidence-based research contributions (Hanssens, 2018; Hulland and Houston, 2020; Hunter and Schmidt, 2004).

Meta-analyses and systematic reviews occupy a uniquely important place in the research landscape. Unlike individual empirical studies, which are often constrained by sample size, geographic context or methodological choices, these synthesis approaches aggregate evidence across multiple studies, thereby reducing bias, enhancing reliability and generating broader empirical generalizations. Meta-analysis, in particular, employs statistical techniques to combine the results of multiple studies addressing the same research question, offering a cumulative weight of evidence that no single study could achieve alone. Systematic reviews, by contrast, provide comprehensive and transparent qualitative assessments of the existing literature, making them invaluable for theory building, identifying research gaps and critically evaluating the current state of knowledge in a given field. Together, these methods represent powerful tools for advancing both theoretical frameworks and evidence-based practice in service research.

The nine papers included in this special issue reflect the breadth and depth of contemporary service research. Five papers employ meta-analytic methods to statistically synthesize findings across studies, while four papers adopt systematic review approaches to generate qualitative and conceptual insights into important service phenomena. Collectively, these contributions address a wide range of topics, identify critical gaps in literature and offer meaningful implications for both researchers and practitioners in the service domain.

The advancement of scientific knowledge depends not only on the generation of new findings but also on the corroboration of findings across independent studies, contexts and methodologies (Babin et al., 2021). Corroboration – the process through which a scientific claim is confirmed and strengthened by multiple independent lines of evidence – lies at the heart of rigorous inquiry (Popper, 1959). In marketing and service research, however, the dominant reliance on single empirical studies has posed a challenge to this principle. Individual studies, however carefully designed, are inherently constrained by a range of limitations that make it difficult to draw broad and reliable conclusions from any single piece of research in isolation. Academic researchers become socialized by the academic journal review process to believe a “first strike” is necessary to make a “novel” contribution. All too often, journal acceptance puts considerable weight on novelty defined in this way, that true scientific knowledge building is neglected (Babin et al., 2021). When novelty is defined in such a way, a reviewer trying to re-examine some previously published finding faces the hard result of a rejection because “it has already been done.” Meta-analytic approaches attempt to provide some avenue for corroboration and even present procedures that try to assess and correct for the file-drawer effect, which refers to the body of work now published because of a lack of statistical significance.

First, single empirical studies are often limited by sample size and sampling context. A study conducted with a specific population in a particular geographic or cultural setting may produce results that do not generalize beyond that context (Hunter and Schmidt, 2004). For example, findings on service quality perceptions derived from a sample of North American consumers may not accurately reflect the experiences of consumers in Asia or Europe, where cultural norms and service expectations differ considerably. Second, individual studies are susceptible to methodological idiosyncrasies, including variations in measurement instruments, construct operationalizations and analytical approaches, all of which can introduce noise and inconsistency into the literature (Palmatier et al., 2006, 2018). Third, publication bias – the tendency for journals to favor statistically significant results over null findings – further distorts the cumulative body of evidence, creating an inflated and potentially misleading picture of the phenomena under investigation (Rothstein et al., 2005).

These limitations are particularly pronounced in service research, a field characterized by a vast and rapidly growing body of empirical studies that frequently produce inconsistent or even contradictory findings. The diversity of service contexts – spanning healthcare, hospitality, retail, financial services and beyond – further compounds the challenge of drawing generalizable conclusions from any single study. Empirical generalizations are the lifeblood of a cumulative science, yet they remain elusive when research is evaluated on a study-by-study basis rather than synthesized across the broader literature (Borenstein et al., 2009; Hanssens, 2018).

Meta-analyses and systematic reviews directly address the limitations of single empirical studies by aggregating and synthesizing evidence across multiple independent investigations. In doing so, they provide the cumulative foundation on which marketing knowledge advances. Rather than relying on the findings of any one study, these evidence-synthesis approaches draw on the collective weight of the literature to identify recurring patterns, reconcile inconsistent findings and generate conclusions that are generally more robust and generalizable than those derived from isolated studies (Hulland and Houston, 2020; Palmatier et al., 2018).

Systematic reviews accomplish this through a transparent and replicable process used to identify, evaluate and synthesize all relevant studies addressing a clearly defined marketing question. This structured approach reduces the subjectivity often associated with traditional narrative reviews, in which study selection and interpretation may be influenced by the reviewer's prior assumptions or theoretical preferences. By systematically examining the available evidence, review studies help ensure that conclusions are grounded in the full body of relevant marketing research rather than a selective subset of studies (Palmatier et al., 2018).

Meta-analyses extend this process by statistically combining the quantitative findings of multiple studies to produce pooled effect-size estimates that better reflect the underlying magnitude of relationships across contexts. This statistical integration increases precision by leveraging larger combined samples and enables researchers to test moderators that explain why effects vary across industries, consumer groups or research settings. In marketing, such analyses have been especially valuable for clarifying boundary conditions, refining theory and informing managerial practice in areas such as relationship marketing, advertising effectiveness, innovation adoption and customer satisfaction (Hulland and Houston, 2020; Eisend, 2015). Accordingly, meta-analyses do not merely confirm prior findings – they strengthen theory development and provide a more reliable evidentiary base for cumulative progress in marketing literature.

A cautionary note is in order. The ability to synthesize the literature can be hampered by poor reporting and uncooperative members of the research community. Researchers pour through hundreds of articles to find a few with reporting complete enough to be used in a meta-analysis. All too often, basic descriptive statistics are not provided or details in calculations are missing. For instance, means are often reported without standard deviations or standard errors. Sample sizes by experimental condition are often missing. Studies that use SEM often report correlations between factors but seldom provide detail as to whether the raw correlation estimates are disattenuated for measurement error. In other words, were they computed by the SEM software (AMOS, lavaan, LISREL, etc.)? If so, they are almost certainly disattenuated. If not, they are almost certainly not corrected for measurement error. Furthermore, researchers often are unresponsive to requests for more details about data from recently published studies or uneager to reply to requests appealing to the grey (unpublished) literature. The preciseness of research syntheses depends on a cooperative research community.

The case for synthesis research in marketing theory and practice has never been stronger. As the service literature continues to expand rapidly pace, the need to consolidate, evaluate and extend accumulated knowledge becomes increasingly urgent. Scholars in marketing have argued that the discipline should place greater emphasis on research that produces empirical generalizations – findings that hold across studies, contexts and populations – rather than relying primarily on isolated single-study contributions that may add only incrementally to a fragmented evidence base (Hulland and Houston, 2020; Palmatier et al., 2018). Recent meta-analytic work in marketing further demonstrates how synthesis research can resolve longstanding theoretical debates and provide clearer estimates of core relationships, such as the drivers of customer satisfaction and marketing effectiveness.

In the service domain specifically, questions concerning the antecedents and outcomes of service quality, customer satisfaction, customer loyalty, customer-perceived value and service innovation have been examined in hundreds of independent studies over the past several decades. Without systematic synthesis, it is difficult for researchers, managers and policymakers to determine which findings are robust and which are contingent on particular methods, industries or cultural settings.

Moreover, the growing complexity of contemporary service environments – shaped by digital transformation, artificial intelligence, omnichannel journeys, platform ecosystems and shifting customer expectations – makes the need for synthesis research even more acute. As new streams of service research emerge around AI-enabled service encounters, automated customer interfaces, personalization and hybrid human-machine service systems, systematic reviews and meta-analyses will be essential for mapping the intellectual landscape, identifying what is known and what remains uncertain and guiding the next generation of theoretical and empirical inquiry. In short, synthesis research is no longer supplementary to service scholarship; it is increasingly central to cumulative progress in both service theory and practice.

This special issue brings together nine rigorously conducted studies – five meta-analyses and four systematic reviews – that collectively advance understanding of service theory and practice across a broad range of topics, industries and theoretical perspectives. Together, these papers demonstrate the value of synthesis research in consolidating fragmented evidence, resolving empirical inconsistencies and generating new theoretical insights that individual empirical studies cannot achieve on their own.

The first article by Song et al. (2026) addresses a critical frontier in service research: consumer adoption of service robots. Drawing on sociotechnical theory, the study synthesizes evidence from 81 independent studies to develop an integrated framework that combines the Service Robot Acceptance Model (sRAM) and the Interactive Technology Acceptance Model (iTAM). This framework highlights how human–robot interaction shapes consumer perceived benefits and risks which further influence consumer perceived trust and then the use intention. The findings show that perceived benefits strengthen trust in service robots, whereas perceived risks, particularly privacy concerns and technology anxiety, undermine trust and reduce adoption intentions. Trust, in turn, emerges as a key mechanism linking these perceptions to consumers' willingness to engage with robotic services. By reconciling contradictory findings and offering a comprehensive, empirically grounded model of service robot adoption, this meta-analysis makes an important contribution to the service innovation literature. It also provides actionable guidance for service firms seeking to design and deploy robotic technologies in ways that align with consumer psychology, trust formation and relational expectations.

The second article by Yan et al. (2006) addresses a critical yet underexplored dimension of service behavior: proactive customer service performance (PCSP). Drawing on a comprehensive meta-analysis of 116 studies, the study examines 23 antecedents across multiple domains, including job attitudes, leadership behaviors, workplace factors and individual characteristics. The findings identify thriving at work as the strongest predictor of PCSP, followed by mindfulness, service climate, work engagement and transformational leadership. Importantly, the study also demonstrates that national cultural dimensions, measurement approaches and time lag significantly moderate several of these relationships, helping to explain inconsistencies in prior research. As the first integrative meta-analytic framework of PCSP antecedents across the broader management context, this study makes a substantial contribution to the service management and organizational behavior literatures, while offering evidence-based guidance for managers seeking to foster proactive service cultures.

The third article by Chefor and Chefor (2026) examines a topic of enduring theoretical and practical significance in service research: the role of service providers' physical attractiveness (PA) in shaping customer responses. Using meta-analytic techniques to synthesize prior research, the study addresses longstanding inconsistencies in literature and responds to growing interest in reducing human bias through technologies such as artificial intelligence. The findings indicate that PA has a moderate overall effect on service outcomes, although its magnitude and direction vary substantially across contexts – ranging from slightly negative to moderately positive depending on the outcome assessed and the methodological approach employed. Through meta-regression, the authors identify several contextual and methodological factors that explain this heterogeneity, while meta-analytic structural equation modeling shows that social perceptions operate as a key mediating mechanism linking PA to service outcomes. By providing a robust and generalizable framework for understanding the “beauty premium” in service settings and clarifying its boundary conditions, this study advances service encounter theory and contributes to the broader literature on consumer judgment and decision-making.

The fourth article by Nadroo et al. (2026) presents a meta-analytic framework grounded in parasocial relationship theory, source credibility theory and the theory of planned behavior to synthesize and resolve inconsistencies in the literature on parasocial relationships and their influence on consumer purchase intentions. Drawing on 87 empirical studies encompassing over 32,000 participants across 15 countries, the study employs meta-analytic bivariate analysis and moderation techniques to examine both the direction and strength of key relationships. The findings reveal that perceived similarity, engagement, trustworthiness and brand credibility positively shape consumer attitudes, which in turn serve as the primary driver of purchase intentions. Notably, attractiveness exerts a negative effect on consumer attitudes, while perceived utility, expertise and sponsorship disclosure show no significant influence. Moderation analyses further demonstrate that these relationships vary as a function of contextual factors – including country economic status, Internet penetration and cultural orientation – as well as methodological characteristics such as gender composition, research method, age group and sample size. By systematically identifying these sources of variation, the study resolves longstanding inconsistencies in the parasocial relationships literature and advances an integrated theoretical understanding of how parasocial dynamics shape consumer behavior in contemporary influencer and celebrity marketing contexts. The study also offers actionable implications for marketers seeking to strategically leverage parasocial relationships to enhance brand credibility and drive purchase behavior across diverse consumer segments.

The fifth article by Wei et al. (2026) investigates the conditions under which service innovation enhances or diminishes firm performance, drawing on Teece's (1986) profiting from innovation (PFI) framework. Synthesizing evidence from 72 studies through meta-regression and subgroup analysis, the study confirms that service innovation generally improves firm performance, but that its effectiveness varies considerably depending on environmental and organizational conditions. Notably, the positive impact is more pronounced in nations with a lower degree of service economy – where appropriability regimes are tighter and imitation is more difficult – than in those with a higher degree. Importantly, this pattern shifts following the COVID-19 pandemic: whereas the advantage of low-service-economy nations is statistically significant before the pandemic, it disappears dramatically in the post-pandemic period, as the gap between the two groups becomes nonsignificant – driven primarily by a decline in the innovation–performance relationship among low-service-economy nations rather than a substantial rise among high-service-economy nations. At the firm level, the study finds that service innovation fails to translate into improved performance in the absence of strong market orientation or effective leadership, while frontline employee commitment also emerges as a significant organizational enabler. By contrast, technological turbulence and learning orientation do not significantly moderate the service innovation–performance relationship, a finding that productively distinguishes between the antecedents of service innovation and the conditions that determine its effectiveness. By systematically mapping these boundary conditions, the study makes an important contribution to the service strategy literature and offers actionable guidance for managers and policymakers navigating the complex interplay between innovation, context and performance outcomes.

The sixth article by Espinet and Miravitlles (2026) offers a comprehensive systematic review of the literature on service firms' internationalization entry mode choices, synthesizing 4 decades of research from 1977 to 2020. Analyzing 307 articles published across 91 journals, the study employs both bibliometric and content analysis to evaluate the applicability of traditional internationalization theories – originally developed in manufacturing contexts – to service industries. The findings reveal that five dominant theoretical frameworks underpin this body of work: the eclectic paradigm, process model theories, internalization theory, the resource-based view and network theory. While the literature broadly acknowledges that service firms exhibit distinct internationalization behaviors, most scholars advocate for adapting existing theories rather than developing entirely new ones. However, there remains limited consensus regarding how such adaptations should be conceptualized and operationalized. By systematically mapping the intellectual structure of the field and highlighting divergent scholarly perspectives on theory adequacy, this study makes a meaningful contribution to international service management research and identifies important directions for future theory development, particularly toward more coherent and service-specific applications of established frameworks.

The seventh article by Biesinger et al. (2026) shifts focus to the organizational dynamics of servitization, developing a practitioner-oriented framework to synthesize the literature on servitization and organizational learning. Drawing on the concept of the learning organization and building on DiBella and Nevis's framework, the study conducts a framework-based systematic review of 52 studies and conceptualizes servitization as a continuous, cyclical learning process shaped by learning orientations and facilitating factors. The findings indicate that successful servitization depends on aligning organizational learning with service-oriented value creation, particularly through shifts toward external knowledge sourcing, value-in-use and customer-centric solution development. Facilitating factors such as leadership, digital infrastructure and cross-functional collaboration are identified as critical enablers of this transformation. Crucially, the study demonstrates that servitization is not a linear progression but a dynamic, non-linear process influenced by interrelated challenges at the individual, organizational, technological and ecosystem levels – a finding that helps explain why firms frequently struggle or regress in their servitization efforts. By reframing servitization as a learning-driven transformation, this study advances theoretical understanding while offering practical guidance for managers designing and implementing service transition strategies.

The eighth article by Nijhawan et al. (2026) undertakes a hybrid systematic literature review to synthesize the rapidly expanding domain of transformative service research (TSR), tracing its theoretical evolution, consolidating its conceptual foundations and identifying avenues for future inquiry. Drawing on a combination of systematic review, bibliographic coupling of 247 studies and content analysis guided by the theory–context–characteristics–methodology (TCCM) framework, the study develops a comprehensive conceptual framework organized around four major thematic areas: designing meaningful service experiences, enhancing customer engagement, orchestrating systemic well-being and enabling social upliftment. A distinctive contribution of the study lies in its recognition that transformative service processes may generate both positive and unintended negative outcomes. By incorporating this dual perspective, the framework offers a more balanced and realistic account of TSR and helps explain inconsistencies in prior findings. Overall, the study advances TSR by providing a holistic, multi-level framework that connects service design, resource integration and well-being outcomes across individual, organizational and societal levels, while positioning TSR as a critical lens for understanding how service systems contribute to human well-being and broader social impact.

The ninth article by Özispa (2026) provides a comprehensive synthesis of the evolution of service quality gap models since Parasuraman et al.'s original framework, drawing on a conceptual review of 183 publications to analyze 14 revised models developed between 1987 and 2022. The study finds that the original gap model remains highly influential, with approximately 93% of subsequent models building on its core structure, while newer models introduce additional gaps and increased complexity – ranging from 3 to 14 gaps – to address the limitations of the original framework in contemporary service contexts. A key trend identified is the growing emphasis on internal service quality and employee perceptions, reflecting recognition that customer satisfaction is deeply intertwined with employee experience. More recent models also incorporate technology-driven service delivery, addressing challenges related to automation, digital platforms and evolving customer expectations, with sector-specific adaptations particularly prominent in technology, transportation, tourism and healthcare. By systematically categorizing these models and tracing the forces driving their development, this study makes a valuable contribution to service quality theory and offers practical guidance for organizations seeking to select and adapt measurement frameworks appropriate to their specific service contexts.

Taken together, the nine papers in this special issue converge on a foundational insight: service outcomes are fundamentally context-dependent. Rather than universal relationships, the links between service constructs and performance are consistently moderated by factors such as national economic conditions, cultural dimensions, demographic characteristics and industry settings. Wei et al. (2026), Nadroo et al. (2026), Chefor and Chefor (2026) and Yan et al. (2026) each demonstrate this in distinct domains, collectively reinforcing the need for boundary-condition-aware theoretical frameworks – and highlighting synthesis methods as uniquely powerful tools for revealing such moderating dynamics.

A second theme running through the issue is the deepening entanglement of technology and human factors in service delivery. Song et al.'s (2026) meta-analysis shows that robot adoption hinges not only on functional attributes but on perceived benefits, risks and trust while Özispa's (2026) historical review traces how digitalization has reshaped service quality frameworks over time. Chefor and Chefor (2026) push this further by raising the question of whether AI might mitigate human bias in service encounters. Across these contributions, technology and human factors emerge not as opposing forces but as intertwined elements requiring integrated theoretical treatment.

The papers also share a multi-level view of value creation. Nijhawan et al. (2026) show how service ecosystems generate cascading effects from individual well-being to societal outcomes, while Wei et al. (2026) and Biesinger et al. (2026) underscore the organizational and ecosystem conditions that mediate these dynamics. Importantly, Nijhawan et al. (2026) also acknowledge the potential for negative outcomes such as value co-destruction and resource misallocation – offering a more balanced perspective than the literature has typically provided.

Finally, the issue raises persistent questions about theoretical adequacy. Whether adapting established frameworks or building new ones, contributors consistently find that existing theories strain under the complexity of modern service environments. Espinet and Miravitlles (2026) note scholarly consensus on the need for adaptation but little agreement on method; Özispa (2026) documents continuous refinement of the foundational Parasuraman et al. model and Song et al. (2026) propose a unified synthesis of competing technology acceptance frameworks. Together, these papers affirm that the discipline's theoretical toolkit must evolve continuously – and that systematic review and meta-analysis are among its most generative instruments for doing so.

The papers assembled in this special issue collectively demonstrate the transformative potential of synthesis research – meta-analyses and systematic reviews – for advancing service theory and informing evidence-based practice. Yet, taken together, they also cast light on the considerable terrain that remains unmapped. As Babin et al. (2021) argue, scientifically grounded knowledge in business disciplines cannot be built on single empirical studies alone; rather, it depends on the accumulation of independently corroborated findings that establish not only internal reliability but also external validity and generalizability across populations and conditions. In a field as contextually diverse and practically consequential as service research, this imperative is particularly acute. The dominant publication culture – which continues to reward novelty and statistical significance over corroboration and synthesis (Babin et al., 2021) – has left many service domains rich in primary studies but starved of the integrative scholarship needed to transform those studies into stubborn, actionable facts. We therefore call on scholars to turn their attention to the following underexplored areas where the primary literature has matured sufficiently to reward – and indeed demand – systematic synthesis.

First, the antecedents and consequences of customer engagement in digital and social media service contexts represent an urgent priority. Despite an explosion of empirical work on this topic over the past decade, findings remain fragmented and at times contradictory, with substantial heterogeneity across platforms, industries and measurement approaches. Key questions remain unresolved: What drives customers to engage deeply with service brands in digital environments, and what are the downstream consequences of that engagement for loyalty, advocacy and firm performance? How do platform characteristics, content type and service industry moderate these relationships? A comprehensive meta-analysis in this domain could clarify the relative strength of cognitive, emotional and behavioral engagement dimensions, identify the contextual moderators that account for inconsistencies and establish effect-size benchmarks that give future researchers a theoretically grounded baseline – moving the field, in Babin et al.'s (2021) terms, from significant difference toward significant sameness. As digital service interactions continue to proliferate and diversify, the need for such integrative evidence has never been more pressing.

Second, the effectiveness of personalization strategies in service delivery across industries remains poorly synthesized. While numerous studies have examined personalization in specific sectors such as retail, healthcare and financial services, no comprehensive meta-analytic framework has yet integrated these findings to assess the boundary conditions under which personalization enhances – or potentially undermines – consumer satisfaction, trust and loyalty. This gap is particularly significant given the rapid advancement of AI-driven personalization technologies, which are transforming the scale and sophistication with which service firms can tailor their offerings to individual customers. Yet, the very novelty of these technologies means that their effects on consumer responses are still poorly understood, and early findings are far from consistent. A systematic synthesis in this domain would not only provide theoretical clarity on the mechanisms and moderators of personalization effects but also deliver directly actionable guidance for service managers navigating a rapidly evolving technological landscape in which the risks of over-personalization and privacy concern are as real as the potential rewards.

Third, the management of service ecosystems involving multiple actors and value co-creation processes has attracted increasing theoretical attention, yet empirical findings across studies remain difficult to compare and integrate due to heterogeneous operationalizations of ecosystem boundaries, actor roles and value outcomes. The absence of a unifying synthesis is particularly consequential in this domain, as the growing complexity of multi-actor service systems – spanning digital platforms, public services, healthcare networks and collaborative consumption contexts – demands a clearer and more coherent theoretical foundation than the current fragmented literature can provide. Scholars have proposed a variety of conceptual frameworks for understanding ecosystem dynamics, but without systematic synthesis it remains unclear which frameworks have received the strongest empirical support, which boundary conditions shape the effectiveness of different value co-creation configurations and where the most significant theoretical gaps lie. A systematic review method could map the intellectual structure of this literature, surface areas of conceptual consensus and identify the theoretical gaps most in need of primary research attention. In doing so, it would not only consolidate existing knowledge but also provide a much-needed roadmap for scholars seeking to develop more robust, service-specific frameworks capable of capturing the multi-level, relational and dynamic nature of value co-creation in complex service ecosystems.

Fourth, the impact of frontline employee characteristics on service quality and customer outcomes remains a largely unsynthesized area despite its clear theoretical and managerial importance. Scattered findings across industries and national contexts suggest that these effects on service interactions are highly contingent on organizational culture, leadership support and customer demographics – precisely the kind of moderated heterogeneity that meta-analytic techniques are uniquely suited to unpack. This challenge is further complicated by the accelerating integration of artificial intelligence and service robots into frontline service delivery, introducing an entirely new layer of complexity to the human–technology interface that has yet to be comprehensively examined through synthesis research. As service organizations increasingly deploy AI-powered systems and robotic technologies alongside human employees, fundamental questions arise about how the interplay between human factors and technological capability shapes customer perceptions of service quality, relational warmth and overall experience. A meta-analytic synthesis in this domain could not only clarify the direct and relative effects of frontline service agents – both human and non-human – on service outcomes but also map the boundary conditions introduced by varying levels of human–robot collaboration. In doing so, such a synthesis would provide both theoretical insight and actionable guidance for service managers designing hybrid workforces that are simultaneously responsive to human relational dynamics, technologically enabled and oriented toward superior customer experience.

Fifth, the relationship between organizational culture and service innovation capacity has accumulated a body of primary research that, to date, lacks a comprehensive integrative treatment. While individual studies have examined how specific cultural dimensions – such as collectivism versus individualism, uncertainty avoidance and power distance – shape an organization's capacity to generate and implement service innovations, these findings remain scattered across disciplines, industries and national contexts, making it difficult to draw confident generalizations. The absence of synthesis research in this domain is particularly consequential given the growing recognition that organizational culture is not merely a background condition but an active enabler or inhibitor of the innovation processes upon which service firms increasingly depend for competitive differentiation and long-term performance. Systematic synthesis could resolve ongoing debates about which cultural dimensions most reliably enable service innovation, how organizational culture interacts with leadership style and market orientation to condition innovation outcomes and how these dynamics vary across national and industry contexts. Beyond resolving these empirical inconsistencies, a well-designed meta-analysis could also illuminate the mechanisms through which culture exerts its influence – whether through employee creativity and risk tolerance, inter-functional collaboration or knowledge-sharing practices – thereby providing scholars with a more coherent theoretical framework while equipping practitioners with the evidence base needed to foster the cultural conditions most conducive to sustained service innovation.

Each of these areas represents a domain where the existing primary literature is sufficiently rich to reward synthesis but where the kind of comprehensive, methodologically rigorous meta-analyses and systematic reviews that characterize the best contributions to this special issue have yet to be conducted. Babin et al. (2021) are direct in their prescription: journals must be more open to publishing well-designed synthesis studies, and scholars must be willing to undertake them even in the absence of the novelty premium that the current publication culture rewards. The service research community would do well to heed this call. As the present special issue demonstrates, synthesis research does not merely consolidate what is already known – it generates new theoretical insight, resolves empirical contradictions, reveals boundary conditions invisible to single studies and ultimately moves the discipline closer to the evidence-based, practically relevant body of knowledge it aspires to become.

This special issue of the Journal of Service Theory and Practice was conceived at a pivotal moment in the evolution of service research – a moment marked by both extraordinary intellectual richness and the formidable challenge of making coherent scientific sense of a literature that now spans thousands of empirical studies across numerous service industries, theoretical traditions and methodological approaches. The nine papers assembled in this issue provide a collective and compelling demonstration that rigorous synthesis research – particularly meta-analysis and systematic review – represents one of the most powerful tools available for addressing that challenge. By systematically aggregating, evaluating and integrating the findings of prior studies, these contributions advance service theory and practice in ways that transcend what any single empirical investigation, however well executed, could achieve.

The importance of cumulative, synthesis-driven knowledge development cannot be overstated. Scientific progress depends not simply on the accumulation of isolated findings, but on the replication, corroboration and boundary testing of those findings across independent studies, methods and contexts. Through this process, context-bound or fragile results can be distinguished from relationships that are robust and generalizable. Meta-analyses and systematic reviews are the principal mechanisms through which this cumulative process is formalized and accelerated, transforming dispersed evidence into a more coherent and dependable body of knowledge. In marketing scholarship, empirical generalizations have been described as essential to cumulative science because they identify patterns that persist across settings and over time (Hanssens, 2018; Hulland and Houston, 2020). Recent editorial guidance in leading journals has similarly emphasized that high-quality review research is indispensable for theory refinement, managerial relevance and evidence-based decision-making (Palmatier et al., 2018). The articles in this special issue illustrate the breadth of questions that synthesis research can address within service scholarship. Yet they also highlight how much remains to be done. Large and strategically important areas of the service literature – including AI-enabled service encounters, omnichannel customer experience, service inclusion and well-being, sustainability in services, frontline employee adaptation and cross-cultural service behavior – still await the kind of rigorous synthetic treatment that can convert dispersed primary findings into reliable theoretical insight and actionable managerial guidance. As service systems become increasingly digital, data-intensive and globally interconnected, the value of synthesis research will only grow.

We therefore close this editorial with a strong encouragement to the service and marketing research communities to continue investing in synthesis research as a central vehicle for scientific progress. We encourage doctoral programs to train the next generation of scholars in meta-analysis, systematic review and emerging evidence-synthesis methods alongside traditional primary research designs. We encourage journals to provide visible and respected outlets for high-quality synthesis scholarship and to recognize the distinctive contribution such work makes to cumulative knowledge. We also encourage funding bodies and research institutions to support the large-scale, collaborative review projects increasingly required by the scope and complexity of contemporary service research. The unanswered questions in service theory and practice are too consequential – for consumers, organizations, employees and society – to be addressed solely through the slow and uncertain accumulation of disconnected studies. Rigorous synthesis research offers a faster, more transparent and more reliable pathway to the generalizable knowledge the discipline needs. We hope this special issue serves not only as an exemplar of that potential but also as an inspiration for the important work that lies ahead.