IMPLEMENTATION OF THE THEORY OF PLANNED BEHAVIOR IN THE PRIMARY AND BUSINESS ECONOMIC SECTORS: A SYSTEMATIC LITERATURE REVIEW

How to cite this paper: Christodoulaki, I., Sahinidis, A. G., & Tourna, E. (2024)


INTRODUCTION
The theory of reasoned action (TRA) and its later extension, the theory of planned behavior (TPB), are the theories that dominate the scientific discussions about persuasion and behavior change.
The central constructs of the TPB are the "Attitude" which is the belief, which is the probability that an action will lead to a certain outcome, the "Subjective norms" which are the perceptions about the opinion of "Significant others" about a behavior, "Perceived behavioral control" (PBC) which is the extent to which the individual perceives itself of being able to perform the behavior in question and "Intention" which reflects the motivational factors that influence behavior and is also a successful forecaster of behavior (Ajzen, 1991).What distinguishes TRA from TPB is the inclusion of PBC in the model.Furthermore, the TPB has become one of the most widely used psychological theories to explain and predict human behavior and specially to understand the connection between beliefs, attitudes, intentions, and behavior, and could ultimately be used to change people's behavior.
Social psychologists and marketing researchers have long used the TPB with remarkable success in practical applications as it has been widely considered to be effective in predicting intention and behavior (Cooke & French, 2008).The TPB has been used in several studies concerning social behavior and has been widely used in several areas, from health care, (i.e., weight loss, quitting smoking, using drugs) to safety, (i.e., using a seat belt), to social behavior (i.e., environmental habits, suicidal behaviors), consumer technology adoption, eating habits (i.e., consuming organic products), etc.The models of behavior are also consistently robust and replicable in predicting behavior and intentions, and career-related behaviors (Ajzen & Fishbein, 1980;Ajzen, 1987;Sheppard et al., 1988).
Even though the literature on the use of TPB to predict human behavior, in relation to health, eating or consuming habits, misuses, environmentalism, social behavior etc., is colossal, researchers have largely ignored these models for many years to explain or predict managers' business practices and intentions.Researchers in management studies usually used less robust and less predictive approaches such as personality traits, demographics, or even attitudinal approaches.Only during the past couple of decades has the TPB been applied successfully in several circumstances in the primary 1production and business2 sector (P&BS).Krueger and Carsrud (1993) argued that the TPB has enormous potential for entrepreneurship researchers and policymakers, entrepreneurs and consultants could benefit from understanding how intentions are formed and how their beliefs and perceptions motivate them in business.Policy makers also benefit from understanding that a policy initiative will affect business formations only if that policy is perceived in a way that influences attitudes.
The purpose of this article is to identify articles concerning the application of TPB, alone or in combination with other theories in P&BS of the economy, where the subjects of research are the enterprises, the managers, or the employees.
The first aspect of the study was searching the literature by reading the abstracts, which allowed to spot the economy sectors that are studied by researchers.The second stream of review focuses on classifying these articles by sector and by area of interest.Then we identify which other theories are used in combination with TPB to explain business intentions and behaviors.
The literature was mapped to investigate the usefulness of TPB, with basically psychological constructs, on economic decisions of entrepreneurs, managers and producers and finally provide the limitations of the study.
The structure of this paper is as follows.Section 2 analyses the methodology that has been used to conduct the research on the implementation of the TRA and TPB alone or in combination with other theories.Section 3 presents the results of the analysis, i.e., the distribution of articles per year of publication, per economy sector, and theme area.Then the citation analysis is presented; the most influential publications and a year-wise analysis of citations and the journal contribution to the TPB in P&BS.Finally, the analysis presents the articles which combine other theories with TPB in P&BS research.Section 4 contains the conclusions, limitations of the study, future research, and implications.

RESEARCH METHODOLOGY
This section explains the research method used to perform the current systematic literature review.For this literature review, we adopted the rules of the systematic literature review by Xiao and Watson (2019) as it increases reliability, and potentially improves the findings.The methodology consists of three sections: the goal of the present research, the method used to identify the required articles, and the analysis adopted to extract the information needed.

Purpose of the study
To decide which articles to search for, and eventually include in the analysis, we developed a protocol in advance, to document the analysis method and inclusion criteria.We used four criteria: a) The central point of interest: The focus of the analysis was to spot articles about the application of the TPB, alone or in combination with other theories, in the primary production (i.e., agriculture, forestry and fishing) and business sector.
b) The time range: This research examined articles published from 1993 up to 2022, which is an extensive period of 29 years to bring useful understanding to what Krueger and Carsrud (1993) saw as a great potential in using TPB to interpret behavior in business and entrepreneurship.
c) The type of publications: The study includes articles published in journals, having a business focus.Other publications, such as books and conference papers, were not included in the analysis.
d) The language: The analysis covered articles published in journals written in the English language.Articles in other languages were not examined.

The method used to discover relevant articles
The relevant articles in the literature were identified by using an electronic search.The electronic database Scopus was searched to this end, as it is one of the largest databases consisting of scientific peer-reviewed literature and especially journal articles.Keywords like "theory of planned behavior", "theory of reasoned action", "behavioral intention", "subjective norms", "perceived behavioral control", "attitude" AND "business" OR "services" OR "trad*" OR "tourism" OR "agriculture" OR "construction" OR "financ*" OR "entrepreneur*" OR "e-commerce" OR "communication" OR "manufact*" OR "transport*", OR "energy", were used to trace the relevant articles.The outcome of this literature search brought a vast number of articles that had to be examined based on their relevance to this study.The above keywords were chosen to include all the relevant literature of the TPB in relation to the area of interest of this study.Thus, we used also keywords to make sure that the studies retrieved would include business sectors of the economy such as agriculture, construction, finance, trade, communication, transportation, any kind of manufacturing, tourism etc.This search delivered 5,857 articles.
As an inclusion criterion, the time frame between 1993-2022, was chosen so as to cover almost three decades of literature on the subject, from the year that Krueger and Carsrud (1993) saw the great potential of the implementation of TPB in entrepreneurial research, up to, and including 2022.
Then, the authors' names, the title, the abstract, the keywords, the source title, and the year of publication, from the 1,663 identified articles, were exported to a Microsoft Excel spreadsheet.
The next exclusion criteria resulted in the deletion of 22 more papers that were irrelevant to the research scope and 14 articles that were literature reviews.These articles were excluded based on the title.This exclusion resulted in having 1,597 articles for the final review.The abstracts of the remaining articles were independently reviewed, and those referring to the use of TPB in P&BS were retained for further examination.In several cases where the abstract was not explanatory enough about the methods and the scope of the study, the full articles were reviewed to extract the information needed.Finally, another 1,293 articles were also excluded, as the samples studied were either consumers' intentions or students' intentions for choosing a profession or starting a business.This exclusion criterion was applied to end up only with those articles that were related to managerial decisions or decisions taken by the employees within a business entity.
These screening procedures resulted in 334 journal papers in English during 1993-2022, examining the implementation of TPB in several sectors of the real economy to predict or analyse decision-making, having as subjects of their research either managers or employees.
By considering the Preferred Reporting Items for Systematic Reviews and Meta-Analyses, also known as PRISMA (Page et al., 2021), we developed the PRISMA four-phase flow diagram presented below (Figure 1).

Distribution of articles per year of publication
Figure 2 shows the distribution of articles per year of publication.From 1993 to 2008, only one or two relevant articles were published, per annum, involving the implementation of TPB in the P&BS.Between 2012 and 2016 the published articles did not exceed 20 articles per year.From 2017 to 2022 there was an increase in the number of papers published.This trend shows that there is an increasing interest among researchers working on TPB in areas other than psychology, consumer behavior, etc.

Distribution of articles per economic sector (primary and business)
In 1989 the United Nations Statistical Commission suggested an integrated system for classifying activities, goods, and services.Among those is the Broad Economic Categories (BECs) classification 3    95 -Repair of computers and personal and household goods.
As a result, this review does not include articles concerning the public sector and non-market activities (i.e., education, public health, social work activities, activities of households as employers, entertainment etc.).
After further evaluation, the final set of articles extracted from the Scopus database was classified according to the NACE Rev. 2 definition.The majority of studies (35% of the total) were conducted in activities of NACE Section A, i.e., agriculture, forestry and fishing (n = 115).As depicted in Figure 3, between 1993 and 2022, there were several studies (98 publications or 29% of the total) that did not involve just one economy sector, but a cross-sector analysis was performed instead.The third most researched sector (by 9%) was construction (n = 31), followed by tourism (n = 28), finance/insurance (n = 21), manufacturing (n = 11), information/communication (n = 8), wholesale and retail trade (n = 8) and services (n = 7).Finally, there were fewer publications concerning real estate (n = 3), transporting (n = 2) and energy (n = 2).This distribution suggests that researchers found the TPB useful in their studies to explain or predict managers' or employees' intentions, in a wide variety of economy sectors.
In the review, no articles are found referring to NACE code activities such as B -Mining and quarrying, M -Professional, scientific, and technical activities, and 95 -Repair of computers and personal and household goods.Source: Authors' elaboration.

Distribution of articles by thematic areas
During the review of the articles, we observed that researchers were focusing on certain areas in their analysis.As shown in Table 1, the context of 108 publications out of 334 concern "Environmental issues" (32% of the total), which is the most researched theme during the last 28 years.The "green" literature has explored the relationship between environmental issues and various behaviors and involves sustainability (Sarkar et  The second most researched area concerned "Business practices".This category of publications is 25% of the total or 82 articles out of 334.Under "Business practices" were categorized into ethical sales (Oh et  Technology adoption by companies ranks third with 28 publications or 8% the of total articles that used the TPB to examine the behaviors and intentions of managers, or employees.Nine of these articles concern agriculture (Warner et  The next most researched theme was entrepreneurship (5% of the total), followed by waste management (4%), innovation (4%), e-business (3%), animal welfare and health (3%), financing/investments (3%), knowledge sharing (3%), food safety (2%), health and work safety (2%), internationalization (2%), and social responsibility issues (2%).

Citation analysis
The analysis includes a citation analysis (a) by publication and (b) by year of citation (based on the number of citations the articles received each year in the Scopus database).

Citation analysis by publication
The top 18 most influential publications which have more than 100 citations each, are responsible for 42% of the total citations in the field under analysis (see Table 2).Among these, the most cited article, with 945 citations (10% of the total), is Krueger and Carsrud (1993).The authors conducted a crosssector analysis concerning entrepreneurs' intention to start a business and were among the first who realized the potential of the application of TPB in managerial decision-making.Around 300 citations in other publications were reported for Harrison et al. (1997) and Riemenschneider et al. (2003).Both studies performed cross-sector research under the context of technology adoption by companies.This is expected, since the more sectors a publication involves, the less specified it is and the more citations it gets.
Fourth in the ranking with 222 citations is Tohidinia and Mosakhani ( 2010 Out of the 334 articles, the analysis for "crosssector" related publications accounts for 40% of total citations (n = 2,537) and the agricultural sector (including forestry and fishing)-related publications account for 28% of the total (n = 3,657).The third most cited sector is the construction sector accounting for 12% of total citations (n = 1,071).

Year-wise analysis of citations
As we see in Figure 4, the largest number of citations seen in 1993 is affected by the most influential article found in the review which is Krueger and Carsrud (1993).This is somewhat expected, as the authors were among the first to see the great potential in the use of TPB in entrepreneurship, leading the way for future scholars.It is also the oldest article doing a crosssector analysis of entrepreneurial intention.
Although citation count represents the best way to spot the most influential articles, it has attracted some criticism as it favors older publications over recent ones, it does not distinguish between negative or positive citations and the number of citations could be inflated by authors' self-citations (Inkpen & Beamish, 1994).
A higher number of citations, per annum, were found from 2010 up to 2020, where there is an increasing interest in the TPB by more disciplines when adding more variables in the constructs or by combining them with the variables of other theories.
The oldest articles are expected to be more cited than recent publications and this is obvious in the year-wise analysis of citations: 2021 (n = 89), and 2022 (n = 117) have less citations compared to previous years.

Journal contribution to the TPB in primary and business sectors
The 334 articles examined in the review were published in a wide variety of academic journals.This can be seen in Table 3, where we show that 140 articles (42%) were published in different journals.This indicates that the TPB is used by a large variety of disciplines and generally has an important impact across many scientific areas.This is expected, as the TPB is a well-established theory, that helps researchers explain managerial behavior and intentions in a business context.The journal with the highest number of publications is the Journal of Cleaner Production having published 22 TPB-related articles (6.6%), followed by the Sustainability journal having published 18 TPBrelated articles (5.4% of the total).

Use of TPB alone or in combination with other theories in primary production and business
The TPB has been used to explain a large number of managerial behaviors and intentions alone or in combination with other theories.Ajzen (1991) stated that the TPB is flexible because it allows for the inclusion of additional variables if they improve the model's predictive power and can be shown to be conceptually independent of the model's constructs.More recent studies have attempted to improve the predictive power of the TPB by adding extra variables.Figure 5 is a visual presentation of the TPB and the relationships of its main constructs.It describes the relationships between beliefs-attitude-intentions and behavior or beliefs, subjective norms, intentions and behavior, or control beliefs-PBC-intentions and behavior.Based on the literature review from 1993 to 2022, we found that the way the TPB is used is also broad.Table 4 presents all the theories that were used in combination with TPB, in P&BS, to explain the engagement of managers and employees in certain behaviors and the drives behind them.The results show that 233 studies out of the 334, or 69.8% of the total, used the TPB or the TRA.Out Besides the above-mentioned theories or constructs, Table 4 presents several others, each accounting for 0.3% of the total, each with only one publication.All these theories in total account for 12% of the total studies (Figure 6).
The large variety of theories and variables (almost 65 other theories, see Table 4) used in the literature in combination with the TPB, underlines the fact that TPB is used in a wide range of disciplines and covers many themes in the business economy such as business practices, innovation, technology adoption, investments, entrepreneurship, waste management, e-commerce, knowledge sharing, environment, etc.

CONCLUSION
This study conducted a literature review of articles published between 1993 and 2022 concerning the use of TPB to investigate managers' or employees' behaviors and intentions.The central point of interest is to spot articles concerning the implementation of the TPB, alone or in combination with other theories, in primary production (i.e., agriculture, forestry and fishing) and business sectors, beyond its mostly known use in research related to psychology, social behavior, consumer behavior, etc.The purpose of the study is to investigate the ongoing interest of researchers to the TPB in business research, identify the subsectors of the business economy that used the TPB, to map the main themes that their analysis involved.Another goal was to show the flexibility of the TPB and TRA, as they have been used in combination with other theories or have been enhanced using other variables as well.
To this end, the Scopus electronic database was searched with specific, relevant to the study, keywords.The search rendered 5,857 records.The sample was further downsized to 1,663 records by extracting only journal articles in English and in certain disciplines related to the study.the abstracts articles were reviewed independently with the aim of keeping only those articles that meet the scope of the analysis.Thus, all studies having as subjects of research consumers or students were excluded as irrelevant.This process ended with 334 articles reviewing their abstracts and gathering all the useful information, such as the subject, the sector, the theme, and the theories in the studies.The analysis proceeded with a distribution of articles per publication year, per economy sector under NACE codes, per theme area, the most influential publications and a year-wise distribution of citations and journals' contribution to the TPB in P&BS and detects other theories used in combination with TPB in P&BS.
This literature review provides evidence that, even though the TRA and its later extension TPB were initially introduced more than three decades ago, ongoing attention is still being paid to it by researchers, due to its predictive power and its flexibility to be used in combination with other theories and/or constructs.In agriculture and business sectors, the use of TRA and TPB, extended or decomposed, account for 80.3% of the articles extracted (334) from the database and year-wise analysis showed that the most fruitful period was between 2010 and 2022.The rest 19.7% of the articles involve the use of TPB in combination with other theories.There is a large variety of theories and constructs that are used in combination with the TPB, in particular more than 65, and the most common ones are related to technology, innovation and environment such as the technology acceptance model (TAM), technology-organization-environment (TOE), technology regime, unified theory of acceptance and use of technology (UTAUT), innovation diffusion theory (IDT), environmental concern (EC) or environmental sensitivity, perceived environmental benefit and perceived ecological impact variables, new ecological paradigm, Person-environment fit theory, institutional pressures and environmental consciousness, social-ecological systems framework, and corporate environmental market responsiveness (CEMR).
The interest in the TPB is not only vivid, through the years, but it is also broad.Even though the TPA and its extension the TPB were initially used by social psychologists and marketing researchers to investigate peoples' habits, consumers' behavior, etc., the results of the analysis reveal that the TPB has been used successfully in a variety of disciplines among P&BS to investigate managers' and employees' intentions.Even though almost one-third of the articles involve studies conducted in the primary sector (i.e., agriculture, forestry, and fishing), many researchers did a cross-sector analysis indicating that the area of interest is broad.These studies cover almost all sectors leaving out a few sectors of the business economy.The majority of the themes covered by these studies concern environmental issues, new business practices, technology adoption and innovation.Even though the above themes are the most researched in literature, there are plenty of other areas of interest such as entrepreneurship, waste management, e-business, animal welfare and health, knowledge sharing, food safety, internationalization, social responsibility issues etc.All in all, the findings show that the TPB still has the attention of the researchers and is even being used to explain/predict/influence even the most recent environmental concerns in primary production that have been gaining growing importance from 2012 onwards.The diverse publishing outlets show that the application of the TPB is attracting the interest of scholars from different fields.
The current study may serve as a useful for understanding to which extent the TPB has been employed in the domains of P&BS.However, there are still some gaps to be addressed.The main limitations of the study are: 1) the study was based on articles that were published in peer-reviewed academic journals in English only; that is, non-English books, industry reports, and conference presentations were not the focus of the study, which could be explored in future studies; 2) this study is limited to the Scopus database as a source; future studies may use other sources with different scopes to make a solid contribution to the current body of knowledge; 3) the literature research ends in 2022, future studies may extend their search to include the year 2023 and after.
This study has implications for researchers, since the results of the analysis, showed that some sectors in business economics have not attracted the attention of researchers for many years.Research related to the implementation of TPB in business sectors such as mining and quarrying, professional, scientific, and technical activities, and repair of computers and personal household goods, will strengthen the literature on this issue.In addition, we found that the literature on sectors such as real estate, energy and transportation is quite scarce, which may also attract future research interest and contribute to the general literature related to the implementation of TPB in business economics.
Finally, another implication for researchers is that they can draw inspiration from a wide variety of other theories when combined with TPB to strengthen their models for analysing predicted behavior and intentions in management research.

Figure 1 .
Figure 1.Identification of studies

Figure 2 .
Figure 2. Distribution of articles by year of publication ), which is used for economic analysis.Based on this, the European Classification of Economic Activities (NACE) includes the primary sector economic activities which refers to agriculture, forestry, and fishing, hereafter "Agriculture"(Eurostat, 2008, Section A).Under this classification, the business economy includes industry, construction, and services.This refers to economic activities covered by Sections B to J, and L to N, and Division 95 of NACE Rev. 2, and the enterprises that carry out those activities.In detail, these sections are:  B -Mining and quarrying;  C -Manufacturing;  D -Electricity, gas, steam, and airconditioning supply;  E -Water supply, sewerage, waste management and remediation activities;  F -Construction;  G -Wholesale and retail trade; repair of motor vehicles and motorcycles;  H -Transportation and storage;  I -Accommodation and food service activities;  J -Information and communication;  K -Financial and insurance activities;  L -Real estate activities;  M -Professional, scientific, and technical activities; 3 https://unstats.un.org/unsd/trade/classifications/bec.asp N -Administrative and support service activities;

Figure 4 .
Figure 4. Number of citations per year of publication

Figure 5 .
Figure 5. TPB and connections between its main constructs

Figure 6 .
Figure 6.Percentage distribution of articles using TPB standalone or in combination with other theories These studies are published in various journals like the Journal of Cleaner Production, Sustainability journal, and Land Use Policy journal.Several studies TPB TPB and TAM/TOE/Innovation diffusion theory/Technology regime/UTAUT TPB and various theories TPB and eviromental theories (62% of the articles) with only one or two publications per journal, cover a wide variety of other issues supporting the argument for the broad use of the TPB.

Table 3 .
Journal count

Table 4 .
Standalone use of TPB or in combination with other theories (Part 2)