Mapping the literature of integrated marketing communications: A scientometric analysis using CiteSpace

Integrated marketing communication (IMC) is an effective marketing practice in the age of social media. IMC builds customer relationships and enhances brand value by integrating information from multiple channels and strengthening user interaction. The purpose of this study is to present the development process, current hotspots, and future trends of IMC research. Moreover, it explores the characteristics and patterns of IMC research. First, this paper shows the annual literature volume, leading countries, journals, and authors in IMC research through bibliometrics. Then, five hot research topics are identified through keyword co-occurrence analysis, namely IMC theory and models, brand communication, media research, customer research, and marketing strategy. From 1991 to 2020, IMC research is divided into five phases, each of which is related to the enhancement of user interaction. Future IMC research will continue to be user-centered, and IMC research will continue with social media and branding, as well as research on other topics that can further enhance user interactions. This paper also finds that the characteristics of the concept of IMC itself lead to a constant renewal of its connotations, which is one of the reasons why scholars cannot reach a consensus on the concept of IMC.
AcknowledgmentsWe thank Associate Professor Zhenkun Cui of Henan Institute of Science and Technology for his valuable comments during the writing and revision of this paper. The following research projects supported this study: (1) Henan Provincial University Humanities and Social Sciences Research Project No.2022-ZDJH-0099; (2) Henan Provincial University Humanities and Social Sciences Research Project No.2022-ZZJH-158; (3) Henan Province Social Science Planning Project No. 2021BZZ004; and (4) Xinxiang Social Science Federation Research Project No. 2021-167.


INTRODUCTION
Integrated marketing communications (IMC) has been a significant advance in marketing communications for decades. It is widely accepted and used by advertising, marketing, and public relations practitioners. Meanwhile, researchers have explored the impact of IMC from a practical perspective in a wide range of industries such as advertising services (Chen, 2011), hotel industry (Al-Qeeda, 2019), fashion (Henninger et al., 2017), e-commerce (Joseph, 2011), food industry (Dagustani et al., 2016), higher education institutions (Gordon-Isasi et al., 2020), and nonprofit organizations (Henley, 2001).
Currently, IMC is showing its vitality worldwide because of its consumer-centric nature and marketing-based philosophy that provides the basis for user-oriented marketing strategies.
At the same time, IMC is a widely used and widely debated concept on the one side. Despite the numerous studies on IMC, there are various research views, and there has been no consensus on the definition of the concept and scope of IMC (Kliatchko, 2005;Madhavaram et al., 2005;Schultz & Schultz, 1998;Swain, 2004).
Advocates of IMC see it as an up-to-date concept, while skeptics see IMC as a mere management fad topic without substance.
Currently, the articles are primarily focused on the gaming research of IMC. Meanwhile, these debates around IMC continue to contribute to researchers' thinking about the definition, acceptance, leadership, and measurement of IMC and the constant updating of the definition of IMC. During the evolution, there have been dynamic changes in the definition of IMC by both advocates and skeptics. However, no patterns of change inherent in the evolution of IMC have been reported in the literature. In addition, current research on IMC is more often found in research papers, followed by systematic literature reviews with little bibliometric analysis.
The data in this paper were retrieved from Web of Science (WoS) and Scopus databases for IMC literature citation information. First, the paper counts the number of literature by year, using statistical graphs to show the distribution and trends of the literature. Subsequently, a series of keyword co-occurrence graphs were drawn using CiteSpace to show the top contributing countries, journals, and authors in the IMC research area. Finally, the keyword co-occurrence mapping was used to extract burst keywords, identify the evolution of IMC research, and explore future research trends.

Integrated marketing communications
The concept of IMC was first developed in the late 1980s. Schultz (1992) formally put forward the theory of integrated marketing communication, which advocates the multiple aspects of marketing as a whole and multiple means of communication, multi-channel communication, to establish a good relationship with customers. Duncan et al. (1997) suggest that brand relationships should be central to IMC and that the essential elements of IMC should all revolve around brand relationships.
IMC differs from traditional marketing communications approaches in many ways. The most revolutionary is that the consumer has become the focus of marketing (Hartley & Pickton, 1999) rather than the product, channel, price, or promotion. The traditional Four-P theory of marketing communication (product, price, place, and promotion) assumes that sales can be achieved if a company produces a reliable quality product, determines the right price, and uses the appropriate channels, complemented by specific promotions. The Four-P theory is a product-oriented marketing theory from the company's perspective. In order to achieve the consumer-oriented purpose, Schultz (1992) (Hutton, 1996). Other scholars have questioned IMC's theoretical robustness and practical implications (Cornelissen & Lock, 2000).
The American Association of Advertising Agencies (Caywood & Ewing, 1991) defines IMC as a concept that emphasizes the need for synergy in marketing communications programs (Duncan & Caywood, 1996). Duncan and Caywood (1996) identifies brand value as the core of IMC and the importance of perception. In addition, Duncan and Caywood (1996) emphasize the purposeful nature of integration, focusing on maintaining good relationships. On the other hand, Schultz and Schultz (1998) emphasize IMC as a business process and define the actions, objects, and goals of IMC, which is a more comprehensive definition. Kliatchko's (2005) definition emphasizes IMC as both a concept and a process and stresses the importance of brand communication and long-term strategy. Subsequently, Kliatchko (2008) removes the conceptual formulation, emphasizes the audience-oriented character, and specifies IMC's target, content, medium, and outcome.

1989
IMC is a concept of marketing communications planning. It recognizes the added value of a comprehensive plan that evaluates the strategic roles of a variety of communication disciplines -general advertising, direct response, sales promotion, and public relations -and combines these disciplines to provide clarity, consistency, and maximum communication impact (Caywood & Ewing, 1991).
Schultz 1992 IMC is the process of managing all sources of information about a product/service to which a customer or prospect is exposed, which behaviorally moves the consumer toward a sale and maintains customer loyalty (Schultz, 1992).

1992
IMC is the strategic coordination of all messages and media used by an organization to collectively influence its perceived brand value (Duncan & Caywood, 1996). Duncan and Caywood 1996 The process of strategically controlling or influencing all messages and encouraging purposeful dialogue to create and nourish profitable relationships with customers and other stakeholders (Duncan & Caywood, 1996).

Schultz and Schultz 1998
IMC is a strategic business process used to plan, develop, execute, and evaluate coordinated, measurable, persuasive brand communication programs over time with consumers, customers, prospects, and other targeted, relevant external and internal audiences (Schultz & Schultz, 1998).

2005
IMC is the concept and process of strategically managing audience-focused, channel-centered, and results-driven brand communication programs over time (Kliatchko, 2005).

2008
IMC is an audience-driven business process of strategically managing stakeholders, content, channels, and results of brand communication programs (Kliatchko, 2005).

Data selection
The data source for scientometric analysis is citation information. To improve the reliability of the study, two widely used high-quality databases, WoS and Scopus, were selected as data sources. Similar scientometric studies have chosen these two databases (

Definition of search criteria
First, a preliminary literature search was performed. Preliminary searches of the WoS and Scopus databases revealed that the keywords "integrated marketing communication," "integrated marketing communications," and "IMC" could be used. In addition, a review of preliminary search results found that "IMC" has specific meanings across multiple disciplines. In the end, "integrated marketing communication*" was used as the search term, and the search range was from January 1, 1991, to December 31, 2020.

Retrieval and data processing
On May 16, 2021, the search process was performed separately in the WoS and Scopus databases. When searching the WoS database, the search field was "Topic," the search year was 1900-2020, the indexes included "SCI-EXPANDED, SSCI, A&HCI, CPCI-S, ESCI." The search keyword was "integrated marketing communication.*" 218 articles were identified. The search results were exported into text and spreadsheet formats for analysis, statistics, and mapping.
When searching the Scopus database, the search field is "TITLE-ABS-KEY," the search keyword is "integrated marketing communication,*" and the time range is "earlier than 2021." The search results were 465 articles.

Analysis
In analyzing co-occurring terms for analysis of countries, journals, and authors, co-occurrence maps were drawn using data from Scopus and WoS, respectively. In the analysis of burst keywords, data from the two databases were combined for a more macroscopic analysis. In the keyword co-occurrence graph, each node represents a keyword, and the connecting lines represent the strength of association between keywords. The node size represents the number of occurrences of the keyword, and the larger the node area, the more occurrences of the keyword. The color gradient of the nodes represents the year in which the keyword appears, with cooler shades representing earlier years and warmer shades representing more recent years. Finally, the line between the keywords represents the number of times two keywords appear at the same time, and more lines represent a stronger association between the two nodes.
According to the research design, this paper reports the results of several dimensions of scientometric statistics, the parameters of the mapping, the creation of the corresponding statistical tables, and the distillation of the necessary information.

Output overview
The number of articles included in the Scopus (n = 465) is more significant than those included in WoS (n = 218). After discounting the overlapping 149 articles, the search resulted in a total of 534 articles, indicating that these two important databases are essential complements to each other.
The annual number of publications is essential for understanding the development status of a research field. Figure 1 shows the number of IMC literature with duplicates removed and the number of times the literature has been cited.

Countries
The co-occurrence map of countries shows each country's contribution to the research field. To make the image transparent, this paper analyzed the search results from the WoS database using the following parameters "Time Slicing: From 2000 JAN to 2020 DEC, one year per slice; Term Source: title, abstract, author keywords (DE), keywords plus (ID); Node type: Country; Selection criteria: g-index=25; Pruning: none." After adjusting the node size, label font size, and node position, the country co-occurrence map (WoS database) is shown in Figure 2.
In Figure 2, node size represents the amount of literature for that country. The more literature there is, the larger the radius of the node for that country is. The color of the outer circle of the node represents the influence of the literature in that country.
The thicker the line in the outer circle, the stronger the importance. The gradient color within the node represents the age of the literature published in that country, with warm colors representing re-cent publications and cool colors representing previous publications. The line between nodes represents when two countries appear in an article simultaneously, with thicker lines indicating more collaboration. The United States is the most documented and influential country, followed by Spain and the United Kingdom (labeled ENGLAND). It is worth noting that the Spanish node has a warmer color, indicating that the Spanish literature was published later.
Similar parameters were used in the country co-occurrence analysis of the Scopus data (from 1991). After adjustment, the country co-occurrence map (Scopus database) is shown in Figure 3. Again, the number of documents from the United States ranked first in the Scopus database, followed by the United Kingdom and Australia. Figure 3 shows that the USA has the largest number of publications in the Scopus database and the most significant influence, followed by Spain and China.
The centrality indicator represents the size of the country's influence in this research area. Table 2 lists the top 10 countries in both databases. In the WoS database, the United States (centrality = 0.26), Australia (centrality = 0.19), and France (centrality

Journals
The number of citations is the primary indicator of the importance of a journal in a particular field of research. The more times a journal is cited, the  Figure 4 shows the names of the journals that have been cited more than 100 times. The node's size represents how many times it has been cited, while the node's color represents the time it has been cited. The newer the cited time, the darker the outer edge of the node, and vice versa. Each node is a journal, the node's size represents the number of citations, and the node's color represents the link between the nodes. The thicker the link between the two nodes, the closer the topics of the two journals are. It can be seen that multiple journals form a common citation network, which indicates that these journals publish articles on similar topics. Table 3 shows the top 10 most cited journal names, ISSN, the impact factor (2019), and CiteScore (2019).
The number of citations reflects the importance of the journal in the field of research. The most influential of these journals are the Journal of Advertising Research, which has been cit-

Authors
The results showed that 367 authors participated in 213 articles in the WoS database and 598 in 465 articles in the Scopus database.
The parameters used in the analysis of the WoS data are "Time Slicing: From 2000 JAN to 2020 DEC, 1 year per slice; Term Source: title, abstract, author keywords (DE), keywords plus (ID); Node type: Author; Selection criteria: g-index=35; Pruning: none." Figure 5 shows the names of authors with two or more articles.
Don E. Schultz and Philip J. Kitchen are the core authors of IMC studies in the WoS database, and many other authors form a more extensive collaborative network with them.

Figure 5. Author co-occurrence map (WoS database)
Similar analysis parameters were used to analyze Scopus data, except that the starting year was changed to 1991. Figure 6 shows the names of authors with two or more articles. Except for the core authors, the distribution of authors is scattered, and there are few collaborative relationships among them. Schultz is considered one of the most cited advertising scholars, and his research has helped shape advertising and marketing through publications in academic journals, textbooks, and business books. Philip J. Kitchen is a crucial collaborator of Don E. Schultz, and the two have collaborated on more than ten articles.

Topics
WoS and Scopus search results were merged to analyze these topics, removing overlapping records. Investigating the keywords in the articles provides a more detailed understanding of the topics and issues that researchers address in their IMC research. The search results of the two databases are merged, using the parameters "Time Slicing: From 1991 JAN to 2020 DEC, one year per slice; Term Source: title, abstract, author keywords (DE), keywords plus (ID); Node type: Keyword; Selection criteria: g-index=15; Pruning: Pathfinder; Pruning sliced networks; Pruning the merged network." After the clustering operation, the keyword clustering graph shown in Figure 7 was obtained.
Each color area in Figure 7 represents a clustering topic; the larger the area, the more keywords it contains. Five key IMC topics can be derived from the clustering summary, including IMC conceptual exploration, IMC model construction, IMC Implementation, and the IMC meas-   Figure 7. Keyword co-occurrence map in IMC research urement. For example, brand research determines how to establish a brand image, manage brand assets, highlight brand characteristics, and improve brand value. Media research includes multiple media channels, applying social media, measuring the effectiveness of social media marketing, and processing media information. Customer research includes studying customers' online behavior, improving the effectiveness of communication with customers, and enhancing interaction with customers to strengthen customer relationship management, thus increasing customers' perception of the brand and improving their attitude toward the brand. Finally, marketing research includes strategies for specific marketing activities, marketing strategies in e-commerce, how to build a virtuous economic cycle, etc.

Evolution of IMC research
Bursting keywords are research hotspots that appear suddenly at a particular stage, which can help us understand the evolution of research hotspots in IMC research. The parameters used in the analysis are "Time Slicing: From 1991 JAN to 2020 DEC, five years per slice; Term Source: title, abstract, author keywords (DE), keywords plus (ID); Node type: Term/Keyword; Selection criteria: g-index=25; Pruning: Pathfinder, Pruning sliced networks, Pruning the merged network." Switching to the Burstness view in the CiteSpace control panel and setting Gama = 0.8, 12 bursting keywords were obtained and shown in Table 5.
IMC has different concerns and dynamic changes in different periods (Figure 7 and Table 5). The evolution of IMC research topics is related to the rapid advances in information technology and media and can be divided into five stages, each characterized by the following.
Start-up phase (1989)(1990)(1991)(1992)(1993)(1994)(1995)(1996)(1997)(1998)(1999)(2000). The first definition of IMC appeared in 1989, and scholars and practitioners began to discuss the concept and scope of IMC and develop a preliminary understanding. However, there was less relevant literature in this period (Luck & Moffatt, 2009), and no bursting keywords emerged. The landmark was the publication of Schultz's Integrated Marketing Communications in 1993, from which IMC began to be widely disseminated and reached a stage peak in 1996. From 1996 to 2000, the keywords that burst were "advertising," "marketing communications," and "branding." "Marketing communications: then lasted 10 years, while "advertising" and "branding" lasted 15 years.   Social marketing phase (2016-2020). For 2016-2020, bursting keywords include "innovation," "social media marketing," "customer satisfaction," and "word of mouth." These keywords reflect that social marketing is starting to become a new trend. At this stage, highly influential online celebrities began to participate in social media marketing activities, and marketing communication was greatly expanded. At this stage, social media users are growing in spurts. Social media platforms are making full use of big data analysis and user profiling to achieve accurate content pushing to users and even generating content for each user in real-time. At the same time, the fractured spread of social media is widely used, and companies use "word of mouth" as a crucial way to improve integrated brand marketing ( Hot research topics and evolutionary process showed that IMC theory and models, brand communication, media research, customer research, and marketing strategy are the five hot research topics of IMC research. The IMC research can be divided into five stages: IMC initiation stage, IMC formation stage, web 1.0 stage, web 2.0 stage, social media initiation stage, and social media explosion stage.
As for the future research trends, social media and brand building research will continue to be a hot spot for research, and "experiential marketing" will see a growth process. In the foreseeable future, integrated marketing communication will usher in the renewal of concepts and the reconstruction of models to adapt to the new round of technological revolution and changes brought about by user experience innovation.
Considering the regular pattern of IMC concept change and comparing the evolution of IMC concepts and research topics in different periods, the paper found that the content and form of "integration" are constantly changing, which should be one of the reasons why scholars have not reached a consensus on the concept of IMC.
This study has several limitations and offers suggestions for future research. First, the data collected in this paper are limited to English literature in WoS and Scopus databases and do not cover other literature sources. Thus, the results may be biased. Second, most retrieved literature was studied in developed countries, but there is relatively little literature from emerging markets. Future researchers could use more data sources and retrieve literature from non-English speaking countries to obtain more complete results. In addition, future studies could specifically target some countries where ICT is developing faster to obtain more comprehensive results.