Introduction

Thoughtful synthesis of and reflection upon existing research in a specific domain is critical to the advancement of knowledge within a discipline (and often across disciplines). This process of systematic collection, assessment, and integration of existing work forms the core of review papers, “critical evaluations of material that has already been published” (Bem 1995, p. 172). In fact, in some disciplines dedicated, high-impact journals are primarily tasked with publishing only review papers (e.g., Psychology Bulletin).

Review papers can take many forms, including those that are primarily qualitative (i.e., narrative) as well as those that are primarily quantitative (i.e., meta-analyses). In general, marketing journals are more open to meta-analytic review papers than other types, but this is slowly changing. For example, the Journal of the Academy of Marketing Science (JAMS) is open to high-quality review papers of all types.Footnote 1 Similarly, the AMS Review is the sole conceptual-only journal in marketing, and it encourages conceptual articles including reviews. Although getting a review paper through the review process can prove challenging, such papers often garner substantial attention and citation once published (Antonakis et al. 2014; Bettencourt and Houston 2001).

This paper focuses specifically on one type of review paper – the conceptual review. Others have referred to this type of paper as a “review article” (e.g., Barczak 2017; Short 2009) or a “conceptual paper” (e.g., Gilson and Goldberg 2015). However, the term “review article” can be used for a wide variety of different types of reviews, including meta-analyses (Grewal et al. 2018), methodologically-focused assessments (e.g., Scorescu, Warren & Ertekin 2017; Hulland et al. 2018), and theory-focused articles (e.g., Kozlenkova et al. 2014; Rindfleisch and Heide 1997). Similarly, the term “conceptual paper” can be confused with “theoretical paper” (Gilson and Goldberg 2015). In contrast, a conceptual review paper aims to reconcile and then extend past research in a particular domain in a meaningful, conceptual way.

MacInnis (2011), Stewart and Zinkhan (2006), and Yadav (2010) have all observed that the proportion of conceptual articles published in marketing (relative to all types of articles) has declined over time. Many underlying reasons for this negative trend have been suggested, including increasing availability of data and sophisticated analytic tools, lack of conceptual skills training, and insufficient appreciation of conceptual work (particularly in the form of professional rewards). Nonetheless, conceptual work is at least as important for the field’s progress today as it ever was. So how do we overcome this problem?

Yadav (2010) and others have proposed various solutions to combat this declining role for conceptual research. In addition to their excellent suggestions, there’s another step that we can take as scholars: our research can conceptually enrich the field by reviewing extant knowledge, synthesizing findings, and then challenging existing perspectives. The result of this process (i.e., a conceptual review) can be a revitalization of existing theory, the discovery of novel conceptual insights, even the development of new theory. Whereas the task of building a theory “from scratch” can seem daunting, even overwhelming to many researchers, the challenge of collecting, revisiting, and reconsidering existing research often seems more attainable.Footnote 2

With this in mind, the following sections first spell out the primary aims for conceptual reviews and further clarify how they differ from other theory development efforts (as well as meta-analyses). Next, those elements essential to a strong conceptual review are described, followed by the explication of a more specific set of best practices that can be used to distinguish a strong conceptual review from a weak one. Throughout, examples drawn from published conceptual review papers are used to illustrate effective use of many of these core elements.

The primary aim of this paper is to add to the growing conversation in marketing regarding the critical need for theory development and refinement. Its scope is narrower than that of MacInnis (2011) or Yadav (2010), who both provide comprehensive guidance for scholars attempting to make conceptual contributions in marketing. Here, the focus is on how a particular approach, the conceptual review, can aid theory development and refinement.Footnote 3 In doing so, this paper augments recent related work looking at review articles in general (e.g., Hulland and Houston 2020; Palmatier et al. 2018) by placing a greater emphasis on the role of theory. It also provides a complementary perspective to the paper by Jaakkola (2020) that describes types of conceptual papers; the current paper identifies five key elements (stages) critical to all conceptual review papers and suggests best practices.

Theory development and conceptual reviews

Conceptual articles may “present theoretical syntheses (e.g., theoretical reviews, integrative frameworks), develop completely new ideas (e.g., novel theories, propositional inventories, analytical models of unexplored phenomena), or direct attention to substantive domains that have not yet received adequate attention” (Yadav 2010; p. 5). Broadly speaking, these aims can be broken into a primary focus on either (1) synthesizing existing knowledge or (2) developing new ideas. Whereas both forms of conceptual advance can be of considerable value to the field, conceptual review papers focus predominantly on the former objective.

In order to have impact and be credible, the conceptual review process must be conducted in a systematic way. Although more will be said about this later, a systematic (rather than ad hoc) approach helps to ensure that the body of literature reviewed is as comprehensive as possible. Using clear criteria for article inclusion/exclusion helps to assure the reader that the studies reviewed have not been “cherry-picked” to fit any agenda. Further, use of clear systematic procedures allows an interested reader to replicate the study if desired (e.g., Littell et al. 2008).

The process of theory development and refinement can in turn be broken down into five more specific and distinct elements (also referred to as stages below): (1) establishing the scope of the domain under review, (2) integrating and synthesizing extant knowledge within the domain, (3) resolving inconsistencies, (4) highlighting gaps in the existing literature, and (5) setting an agenda for future research.Footnote 4 Each of these critical elements is described more fully below.

Domain and scope

One of the challenges that initially confronts a researcher interested in writing a conceptual review paper is the need to find an appropriate subject. Short (2009; p. 1312) suggests that an ideal topic is “one where a number of conceptual and empirical articles have amassed without previous review efforts or a synthesis of past works.” However, a review can also be appropriate when considerable time has passed since an earlier critical assessment, particularly when the field is very active.

Once the focal domain has been chosen, it is important to define its scope (i.e., specification of what will be included (as well as excluded)), establishing the review’s theoretical, methodological, and substantive boundaries. Furthermore, key underlying assumptions need to be explicitly stated.Footnote 5 Doing so helps both scholars who are new to the topic as well as more established researchers who may not be entirely familiar with the focal domain (e.g., niche scholars (Houston 2019)). For example, Rosario et al. (2020) begin their conceptual review of electronic word-of-mouth (eWOM) processes by noting that the domain under study “highlights a fragmented academic discourse” resulting in “the need to distinguish eWOM from related concepts that may be mislabeled as eWOM”. Similarly, the first step in the conceptual review undertaken by Steinhoff et al. (2019) involves a definition of “the domain of online relationships and their scope, as well as … the key similarities and differences of online and offline relational environments.”

Integrate and synthesize extant knowledge

Although domain specification is an important and necessary first step, it is not unique to the conceptual review process. In contrast, the ability to review and critique existing knowledge is one of the most important elements of conceptual reviews (Hulland and Houston 2020; Yadav 2010). MacInnis (2011; p. 144) refers to this as summarizing, the goal of which “is to take stock of, digesting, recapping, and reducing what is known to a manageable set of key take-ways … Summarization typically takes empirical evidence into account to derive conclusions about what is known.”Footnote 6 To achieve this aim, the conceptual review author must find an effective way to group and present the existing research so as to “to guide the reader toward a better understanding of the focal phenomenon” (Palmatier et al. 2018, p. 4). For example, Dekimpe and Deleersnyder (2018) begin their review of existing business cycle research in marketing by explicitly asking (and then answering) the question “what have we learned?”

Knowledge accumulates in a scholarly domain in an ad hoc manner. This results from idiosyncrasies in data availability, industry access, methodological constraints, the appeal of different theories, etc. To be effective, a conceptual review paper must capture and then synthesize information across studies despite this disparity in individual study focus. This requires an ability to apply inductive reasoning, which “begins with individual observations and then collates these observations into a higher-order set of conclusions” (MacInnis 2011; p.147). For example, Dowling et al. (2020) review published research in marketing that describes consumers’ behavioral biases (i.e., deviations from rational behavior), and then develop a novel conceptual framework that encompasses these findings. Their framework organizes two critical dimensions of this work – three classes of deviations (nonstandard preferences, nonstandard beliefs, and nonstandard decision-making) described across four phases of consumer purchase decision making (need recognition, pre-purchase, purchase, and post-purchase).

As Jaakkola (2020) observes, the line between theory synthesis and a more traditional review is at times a thin one. Whereas literature reviews are primarily focused on organizing and “describing extant knowledge”, conceptual reviews involve looking for “common ground on which to build a new and enhanced conceptualization” (Jaakkola 2020).Footnote 7

Identify and resolve inconsistencies

As research evidence in a particular domain expands, inconsistent findings, rival explanations, and even contradictory predictions arise. One of the key aims of conceptual reviews is to resolve such inconsistencies in a systematic way such that an enhanced conceptual framework is developed (Yadav 2010). As Hulland and Houston (2020; p. 351) note, such “explanations might emerge from theory (e.g., differing or unmeasured moderating or mediating variables), while other might emerge from method (e.g., differing samples, measures, operationalizations), or even simple construct-definition differences (or ambiguities), across studies.”

A great example of this practice is the paper by Khamitov et al. (2020). They systematically review 236 published articles dealing with brand transgressions, service failure and recovery, and product-harm crises. Despite core similarities, however, these three streams of research have developed independently of one another. Khamitov et al. examine these streams to identify inconsistencies, and then propose a conceptual framework that synthesizes them by advancing a unified perspective that enfolds all negative firm events in marketing.Footnote 8

Highlight gaps

A second critical component of all strong conceptual review papers is an ability to look across existing studies to identify important gaps (e.g., key research questions that remain unaddressed) limiting the field’s ability to move forward (Houston & Hulland 2020; Yadav 2010).Footnote 9 MacInnis (2011; p. 143) refers to this as revising, a skill that “involves reconfiguring or taking a novel perspective on something that has already been identified. … Contributions based on revising gain insight from alternative frames of reference.” To be effective in this stage of the conceptual review process, the author must strive to uncover significant new insights. These insights can only emerge from a domain-wide review of existing research; they are typically not apparent from review of individual (or small groups of) studies. For example, in their systematic review of consumers’ visual perception of products, places, and related objects, Sample et al. (2020) draw on work from perceptual psychology, engineering, graphic arts, and architecture to inform a conceptual framework they then use to organize existing marketing findings. Focusing on five main components of visual perception - illuminance, shape, surface color, materiality, and location - helps them to reveal key insights.

There is no easy way to generate these previously unconsidered connections and other non-obvious insights. As Hulland & Houston (2020) observe, there “is no substitute for a process of studying, re-reading, discussing, debating, writing, gathering critical peer feedback, and refining that often takes months of hard effort after a scholar has completed the mechanical review tasks.” Similarly, MacInnis (2011; p. 148) suggests that successful authors should have both substantial expertise with the focal domain and “the creative capacity to see things anew and reconfigure the prevailing view in a different manner.” For example, Rosario et al. (2020) use a motivation-opportunity-ability lens to organize “extant literature from both consumers’ (i.e., eWOM senders and receivers) and marketers’ perspectives”, creating a three-stage eWOM process that represents a re-configuration of traditional eWOM thinking.

Set future research agenda

The fifth and final key element in the conceptual review process involves setting an agenda for future research (i.e., providing a recommendation regarding how the scholarly community interested in the focal domain should advance). This comprehensive research agenda should include specific research questions that might be addressed through further research. For example, these could be focused on studying the domain’s boundary conditions or placing a greater emphasis on its under-investigated aspects. Alternatively, the review might offer suggestions for best practices in terms of appropriate methods and measures to ensure greater comparability across research findings in the future. A strong research agenda will recommend new norms (conceptual, methodological, and substantive) for future application, encourage researchers to focus more attention on persistent, under-studied issues within the domain, and energize scholars to “look beyond boundaries that otherwise restrict learnings to scholars who work with a similar method, theoretical perspective, or context” (Hulland and Houston 2020; p. 352).

For example, near the end of their conceptual review, Dekimpe and Deleersnyder (2018) summarize key insights and then propose areas for future research that involve “(1) a broadening of the research scope, (2) an exploration of relevant contingency factors, and (3) a deepening of the normative recommendations” made by past research. Similarly, Steinhoff et al. (2019) propose a set of tenets and propositions – grounded in their “theoretically grounded and managerial relevant framework” that emerges from their review of the online relationship marketing literature – as part of an agenda for future research in the area.

Conceptual reviews versus meta-analytic reviews

Thus far, the contrast has been between conceptual reviews that emphasize theoretical synthesis, development, and refinement and papers that focus on developing fundamentally new ideas through an identification of what’s novel and then differentiating these new concepts from what is already established. These aims are quite different, and the output of such approaches are distinct. Further, to be completed successfully, conceptual reviews and papers focused on developing new ideas require different conceptual thinking skills (MacInnis 2011; Yadav 2010).

In contrast, the aims of conceptual reviews and meta-analyses are more similar. Using the five key stages of theory development and refinement described earlier, Table 1 summarizes the similarities and differences between these two review paper types. (It is important to note that the entries in Table 1 are meant to be relative to one another (i.e., column versus column), rather than absolute.) The first and last stages are important for all types of reviews, but are not the primary focus.

Table 1 Key elements of conceptual versus meta-analytic review papers
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The primary aim of a meta-analysis is to statistically aggregate individual empirical findings to arrive at a summary main effect estimate. Meta-analyses often also examine the effects of various moderators in enhancing or attenuating this overall main effect (i.e., resolving inconsistencies). In contrast, whereas conceptual reviews do attempt to clarify the theoretical nature of the relationships between constructs (e.g., direct versus indirect, main versus moderating versus mediating), this is not often the primary focus of the review.

Neither meta-analyses nor conceptual reviews are primarily focused on the evaluation of existing methodological approaches. Instead, this is the objective of method-based reviews (e.g., Sorescu et al. 2017). Although methodological considerations need to be accounted for in meta-analyses (primarily in the form of potential moderators), they are not the primary consideration. As for conceptual reviews, whereas methodological elements may be discussed, they are generally not emphasized strongly.

The aim that makes conceptual reviews stand apart from other review paper types is its emphasis on theoretical development and refinement. Whereas meta-analyses are strongly anchored in the examination of relationships and effects that are well-established (i.e. they more often rely on existing or modestly revised theoretical frameworks), conceptual reviews are most effective when they synthesize existing findings, identify gaps and generate new insights, and propose novel ways of thinking about a phenomenon. As MacInnis (2011; p.151) concludes: “not all entities have a sufficient level of development or comparability to make for a useful meta-analysis. Meta-analysis … may be less useful for understanding an entity for which research is emergent, yet not yet entrenched.”

Best practices

Every conceptual review paper is unique, depending on the author’s aims as well as the domain being reviewed and the existing body of available research. However, it is possible to identify a set of best practices than can help result in a superior and effective conceptual review. These practices can be organized into three broad groupings – process, value, and communication. Table 2 summarizes these key practices (described in more detail below).

Table 2 Criteria for evaluating conceptual review papers
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Process

This aspect of writing a conceptual review relates to the care with which the author collects relevant published work (both conceptual and empirical), using a systematic approach to ensure thoroughness as well as reproducibility. Once the source materials are collected, the author must work to provide a fair and balanced assessment of the domain-relevant knowledge, resulting in the identification of key themes / insights.

Reproducible

It is important in any review to provide sufficient details regarding the steps taken to identify and collect relevant published work, to decide whether specific papers (or studies) should be included or excluded, and to systematically evaluate each source document. This gives readers confidence that the resulting insights are based on a careful and detailed assessment of the entire domain rather than a careless and superficial overview.

Thorough

A thorough conceptual review requires the author to identify all potentially relevant and significant papers (both empirical and conceptual) that are relevant to the domain being reviewed. Authors often do a good job of canvassing research published in the field’s top journals (e.g., JAMS, JM, JCR, JMR, Marketing Science), but are less consistent in retrieving papers published in relevant specialty outlets as well as relevant high quality work published in other fields’ journals (e.g., SMJ, JAP). Furthermore, authors need to examine all relevant contributions to the domain being reviewed rather than looking at only a subset (e.g., a random sample of collected papers). Taking care to follow these steps ensures that more meaningful, representative insights will emerge from the review process. In contrast, neglecting important published prior work is likely to undermine the review paper’s impact.

Honest

As domains mature, different theoretical perspectives compete to explain the underlying phenomenon being studied, and inconsistent, contrary empirical findings emerge. When conducting a conceptual review, authors should strive to maintain a balanced discussion of these differences, taking care to present both their strengths and weakness. An overly glowing reflection of existing work fails to highlight problematic issues that need to be resolved, hampering its value for other researchers. On the other hand, the focus of a conceptual review article “should not include an explicitly negative or hostile agenda” (Short 2009, p. 1313).

Focused

There is a tendency for authors, especially those new to writing conceptual reviews, to want to provide a comprehensive assessment of every single paper uncovered in the search phase of the review process. However, overly detailed description of this material is usually counter-productive, as the reader tends to get lost in the minutia of individual studies whereas higher level insights become obscured.

The aim of the conceptual review paper should be to identify important overall themes, and then communicate these effectively to the reader. Although this advice may initially seem at odds with being thorough in the search for source materials, the two steps are actually complementary. The reader wants to know that the author has conducted an exhaustive search to uncover all important published research relating to the phenomenon of interest, but also wants the author to sift through this material and present it in an insightful, value-adding way.

Value

The second grouping of best practices elements shown in Table 2 relates to the overall value of the conceptual review. Specifically, they describe practices that highlight insights not apparent from reading any single paper, that offer novel and engaging ideas, and that provide a clear agenda for future research. For researchers new to a domain, well-crafted conceptual review papers can become a treasured resource, identifying key constructs, laying out widely accepted definitions and assumptions, and offering a conceptual framework rich in terms of both its detail and promise for future research. However, even for veteran researchers conceptual reviews can provide substantial value when they properly emphasize these elements.

Emergent insights

First, it is important to realize that no single paper, however well-constructed, can ever provide the insights possible from a systematic review of related literature. For conceptual review papers, this involves integrating the conceptual ideas presented in individual research papers to arrive at higher level, phenomenon-relevant insights. (This is a process analogous to that used for meta-analysis research, which seeks to statistically agglomerate individual study effects to arrive at higher-level “true” effect size estimates.) These insights emerge from the careful consideration of all relevant papers.

Novel & engaging

It is not enough to simply identify major themes, however. As Short (2009, p. 1314) observes, conceptual review articles “need to provide fresh insights on a number of grounds to truly make a contribution.” Thus, a conceptual review that simply updates an existing review and confirms previous insights has limited value. As discussed earlier, one of the aims of conceptual reviews should be to confront readers with new ways of thinking about the phenomenon in an engaging manner so that the reader comes away “with enthusiasm about ways they might contribute to the ongoing development of the field” (Palmatier et al. 2018, p. 5).

Provide direction

A well-written conceptual review will offer, in addition to novel and engaging insights, a clearly delineated and specific agenda for future research. This critical element lays out specific directions for future research based on the insights that emerge from the review. However, simply generating lists of potential new lines of inquiry is not enough. In order to truly impact the work of others, authors of conceptual review papers need to provide a sense of which unresolved issues require urgent attention, as well as suggesting research avenues that hold the most promise for future research.

Communication

The final set of best practices elements shown in Table 2 is focused on the effective communication of all aspects of the conceptual review. This section focuses specifically on the important roles played by figures and tables. However, other devices can also be used effectively. For example, MacInnis (2011) suggests the use of outlines (including headings and subheadings) to organize materials into categories.

Tables & figures

When used effectively, tables and figures are powerful communications devices. As Palmatier (2016, p. 657) argues, as readers “seek ways to understand [a] paper’s big picture … they often turn first to the figures and tables to understand what the paper offers, before they begin reading.” Figures and tables help summarize large amounts of material, vividly illustrate gaps and opportunities leading to important insights, and provide concrete exemplars of specific phenomena. When used appropriately, these devices clarify the author’s thinking and make the results more amenable to the reader. In contrast, overly detailed tables and figures are often ignored, and can cause confusion. Sometimes it makes sense to break one complex table into several more focused ones, but this can also be overwhelming if taken to the extreme.

In general, tables and figures work best when each one has a clear purpose for being included, when they are concrete and specific, and when they simplify the overly complex. Authors of conceptual review papers should avoid using tables or figures that deal with issues tangential to the primary focus on the underlying phenomenon. It may be appropriate to provide an index or compendium of collected papers in a separate document (e.g., a web appendix), along with other, ancillary material, but such details do not belong in the main part of the review. Furthermore, figures and tables are most effective when they are neither overly simply nor overly complex. (This last point is discussed further in the following two sub-sections.)

Table-specific issues

When used in conceptual reviews, summary tables efficiently summarize past research, clarify definitions, and identify gaps in the existing literature. These tables can help to identify key constructs, note relevant theories, provide definitions, list major assumptions, and/or summarize construct operationalizations. Typically, a separate table would be used for each of these purposes. For example, Khamitov et al. (2020) and Rosario et al. (2020) both use a table placed early in their reviews to define (or clarify) core constructs.

Furthermore, summary tables in conceptual reviews can be used to organize the presentation of existing empirical findings, and strengthen the implications. For example, Lamberton and Stephen (2016) use one of their tables to summarize broad digital, social media, and mobile marketing themes that emerge across different technology eras. Two broad types of summary tables are used for this purpose: summary effects tables and summary gaps tables. Summary effects tables visually organize the preponderance of published empirical evidence supporting a focal phenomenological relationship, refuting the relationship, or finding no significant effect (e.g., see Table 1 in Samiee 1994, Table 5 in Wade and Hulland 2004). This approach can be used both for main as well as moderating effects. Summary gaps tables present a set of key papers (organized in rows) relevant to a focal phenomenon; these are then described across a number of critical differentiating dimensions to emphasize both where extensive research has already been conducted as well as under-examined elements (thereby revealing where gaps exist in the literature).

Figure-specific issues

The boxes and arrows used in figures are valuable in indicating causal connections between constructs, as well as demonstrating a variety of other patterns (Whetten 1989). They are effective when they help “readers see a chain of causation or [visualize] how a third variable intervenes in or moderates a relationship” or when they show “how a particular process unfolds over time” (Sutton and Staw 1995, p. 376). For example, Fig. 3 in Khamitov et al. (2020) illustrates how negative events can intrude on a typical customer journey.

In conceptual review papers, figures most commonly explicate the conceptual framework used to summarize the existing literature as well as (potentially) propose new, previously unstudied constructs and/or relationships. These work best when the proposed model is not overly simplistic (e.g., well-established main effects only); as Palmatier (2016, p. 656) observes, it is “very difficult to publish a main effect-only … paper in a premier journal, because any such model will be highly susceptible to alternative explanations.” For example, Samiee (1994, Figure 1) does an excellent job of integrating disparate literatures on country-of-origin effects and firms’ corporate level decision-making (e.g., product standardization across countries) in the form of a single, visual, integrative framework.

The use of figures relatively early in the conceptual review process (as the author begins to organize the existing literature around emergent themes or insights) helps provide structure that can guide the author’s subsequent exploration. Furthermore, Sutton and Staw (1995) suggest that such figures – when used in the manuscript – can eliminate rambling, inconsistent, and confusing arguments, and generally results in greater coherence and consistency throughout the paper. For example, Fig. 1 in Dowling et al. (2020) elegantly summarizes the proposed framework that they subsequently use to organize their textual narrative. Similarly, Sample, Hagtvedt & Brasel (2020; Figure 2) visually demonstrate the relationships between design elements early in their review.

Conclusion

As Yadav (2010; p.17) laments: “the decline of conceptual articles [in marketing] weakens the theoretical core of the discipline. Therefore, concerted efforts aimed at intellectual renewal are needed”. This paper focuses on the conceptual review paper as one potential methodological approach to effectively develop and refine theory.

Whereas conceptual reviews may seem less daunting, they are nonetheless challenging to write. MacInnis (2011; p. 151) observes that “true integration papers are rare.” In her view, to be effective the scholar must have “a full set of thinking skills” that includes domain expertise, an ability to see differences, an ability to think inductively, an ability to take a creative stance, an ability to present new arguments, and an ability to be persuasive. Although this may all seem overwhelming, the preceding pages attempt to smooth treks down this rough path by first outlining five key elements that are necessary for all strong conceptual reviews, and then fleshing this process out by more specifically identifying related best practices.

Conceptual review papers play a critical role in enhancing the value of extant, domain-specific research not simply by cataloging existing findings, but also by identifying tensions and inconsistencies in the literature, by refining, reconceptualizing, or replacing existing frameworks, by identifying important gaps as well as key insights, and by proposing agendas for future research. Done well, such papers make strong conceptual contributions to marketing.