Self-Initiated Expatriation: A ‘New’ Management Challenge—An Analysis Based on Bibliometrics

: The globalization movement, the growing processes of internationalization and opening of markets that have been observed over recent decades have brought with them a signiﬁcant increase in cross-border movements, with expatriation assuming a prominent role. However, if expatriation is a reality of international markets, over recent years, this concept has taken on different typologies, including self-initiated expatriation. Characterized by the individual initiative that encourages individuals to move beyond their national borders in search of an international work experience, it is critical to understand the phenomena related to SIE. More precisely, we aim to study the problematics of SIE, namely, when it started to be studied and who has published in this area of research, and the identiﬁcation of the main types/sources of publication used to disseminate these works, as well as the main topics that, within the scope of SIE, have been studied. To answer these questions, using information taken from the Scopus database, a qualitative study of an interpretive nature based on bibliometric analysis was performed. At ﬁrst, in order to better understand the phenomenon of expatriation in global terms, 1050 publications were obtained using the item “expatriation”. In a second step, in order to answer the questions posed, the key item of the research focused on the concept “self-initiated expatriation”, with 82 publications identiﬁed. The obtained results allowed us to conclude, among other observations, that although the phenomenon of expatriation has been studied for many years, the particular case of SIE began to gain greater prominence from 2010 onwards, with the highest peak in the number of publications observed in the period between 2012 and 2014. The top ﬁve main authors who are working in this ﬁeld, the main sources where these publications (mostly scientiﬁc articles) are most frequently published, the main countries of origin, and the main approaches developed by the different authors are highlighted here. Theoretical and practical contributions, as well as the political implications of this study, are highlighted in order to encourage the development of more exhaustive studies of SIE, thus contributing to the promotion of policies and practices oriented towards the management of SIE, which can explore the potential skills that these individuals have more deeply and thus contribute to the greater and more effective development of the companies and economies of the countries that host them


Introduction
Individuals have been moving from one country to another since the beginning of human history.Whether for economic, social or political reasons, since the onset of humanity's existence, the search for better conditions has led individuals to move between different countries.Organizations are also examining the best conditions in which to develop their activities.With the movement of globalization, growing internationalization and opening of markets, organizations view these developments as their opportunity to expand their businesses, reaching higher levels of competitiveness.As individuals are the driving force behind these organizations, their responsibility towards all those who are part of them takes on a very important role.The management of human resources thus assumes particular relevance.Additionally, if managing people in the domestic context is a challenge for organizations, this challenge worsens at the international level.It is at this level that we come across the international management of human resources.However, is it really so different to manage human resources domestically as opposed to internationally?In answer to this question, what can immediately be said is that human resource management policies and practices developed by managers are, in essence, the same, since in one or scenario another, we always have to recruit, select, train and reward (Brewster 1991;Brewster and Scullion 1997;Mayrhofer and Brewster 1997).However, when dealing with the management of human resources in an international context, the organization is faced with other variables that are not critical at the domestic level, differentiating it from the international context.We are concerned here with the countries where the organization operates (namely, domestic countries, host countries and third countries), on the one hand, and the types of employees of the international organization (namely, employees from the host country, employees from third countries and employees from the home country, also referred to as expatriates), on the other.Among these three types of employees, expatriates are particularly prominent.Expatriation is understood as the displacement of an employee to a country other than his/her country of origin for the sake of work on an extended assignment and in search of an international career (Howe-Walsh and Schyns 2010; Adams and van de Vijver 2015).The particularity underlying this phenomenon relates to the fact that expatriate employees have their employment guaranteed not only in the company and country of origin but also in the country of their destination, even before leaving the parent company, which is responsible for preparing the departure, as well as the return (repatriation), of these employees.In addition to the entire training process that the employee undertakes in preparation for expatriation, the parent company is also responsible for monitoring the entire process of integration and adaptation to the new country/company by both for employee and his/her family (Lessle et al. 2020;Pustovit 2020).In short, as a whole, the expatriation process encompasses a set of practices developed by the parent company with a view to supporting the expatriate employee not only before expatriation but also during and after the expatriation mission.As a result, the expatriation process entails a set of underlying challenges for the companies and employees involved, insofar as it is a process that requires a strong structure, involving diverse procedures, namely recruitment and selection practices; technical, professional, linguistic and cultural training; the preparation and adaptation of the expatriate and his/her family, accompanied by psychological support; and the preparation and support of the expatriate in terms of the repatriation process.
Underlying this concept of expatriation is the designation of 'business expatriates', defended by McNulty and Brewster (2017), which was largely inspired by the work of Podsakoff et al. (2016) and focuses particularly on the figures of employees with effective links to the parent company, though it extends to all sectors of activity, encompassing multinational companies as well as public and non-governmental organizations.
The reason for this specification becomes relevant if we take account the fact that, over recent years, the figure of the expatriate has taken on increasingly different contours, evolving from the concept we have come to know.That is, expatriation was previously associated with the process whereby an organization sent one (or more) of its employees on an international mission to a branch across borders, and it was very often understood as a strategy used to promote the transmission of the values, philosophy of management and culture of the parent company, which reinforces the concept of the 'business expatriate', defended by McNulty and Brewster (2017).However, with the evolution of societies and the growing number of challenges they face, the concept of expatriation has taken on broader contours.Over recent years, we have witnessed a phenomenon whereby individuals, on their own initiative, seek to develop an international career, thus giving rise to the concept of self-initiated expatriates (SIEs) (Al Ariss and Crowley-Henry 2013).Individual initiative is, without a doubt, the characteristic that, according to Andresen et al. (2020c), defines the self-initiated expatriate when he/she seeks experience abroad.According to the authors (inspired by the work developed by, among others, Dorsch et al. 2012;Begley et al. 2008;and Cerdin and Selmer 2014), this is a process whereby these individuals decide for themselves to seek experience abroad without any organizational support, looking for a new job across borders themselves.Moving away from the concept of expatriation that we addressed above (assigned expatriation), self-initiated expatriation appears as an 'expansion' of this concept, which has contributed to a significant increase in the number of challenges and changes that are progressively facing not only to the self-initiated expatriates but also the target organizations of their interest and, consequently, the human resource management of the latter.
However, what underlies this blossoming of self-expatriates?In parallel with the desire to acquire overseas professional experience, Suutari and Brewster (2000); Doherty et al. (2011) and Richardson and Mallon (2005) are of the opinion that, very often, the decision to proceed with a self-expatriation process is explained by the fact that these individuals face a lack of work opportunities in their countries of origin.Suutari and Brewster (2000) also draw attention to the fact that, contrary to the expatriate assignment, in the case of SIEs, the jobs they perform are in host country organizations or other organizations with an international presence, not in subsidiaries of a parent companies based in their home countries.
However, the differences between the expatriate (with an effective connection to the parent company) and the self-initiated expatriate are not only situated at the level of the motivations that lead them to embrace the foreign assignment.Indeed, contrary to all the support (e.g., financial support) characteristic of assigned expatriation, in the case of self-initiated expatriates, they must bear all the costs underlying the expatriation process (Hussain and Deery 2018;Ceric and Crawford 2016).Ceric and Crawford (2016) also emphasize that these SIEs experience high levels of turnover (between companies and between countries) while not achieving the goals that motivated them to travel across borders.Furthermore, while the assigned expatriate, as we have already mentioned, undertakes an overseas assignment that is duly planned and organized by the parent company, the SIE, when he/she decides to move overseas, can fall into one of two categories: those who decide to go ahead with a professional project across borders with an already concrete idea about the work they aim to carry out (they may or may not have already contacted employers from those countries), and those who decide to go to another country for personal reasons (economic, social, political and family-related, among others) without a concrete definition of the work they intend to carry out (Howe-Walsh and Schyns 2010).
Generally endowed with high levels of qualification, (Andresen and Muskat 2021) is of the opinion that SIEs must become familiar with the cultures of different countries and, consequently, manage their careers, while at the same time adapting to the host organizational culture as well as local work/career norms.
Self-initiated expatriation is a reality that, over recent years, has assumed an increasingly significant presence in different countries (Jokinen et al. 2008).Since, as we have already discussed, these SIEs generally have high levels of qualification (Hussain and Deery 2018), these individuals are important assets for any organization that hosts them.In this sense, it is essential that these organizations give particular importance to their qualifications/their profiles (Froese and Peltokorpi 2011), managing them strategically (Shao and Al Ariss 2020).
However, even if it is true that SIEs constitute a type of international worker, who are assuming an increasingly important role in the labor markets of different countries, the literature on them is still insufficient, having acquired greater prominence only in recent years.In this context, given the relevance of this issue, it is important to understand what kind of attention has been given to SIEs in the literature.Specifically, as the main aims of this article, using a bibliometric analysis, we seek to understand and highlight the nature of the publications in this area and identify who is publishing on SIEs, as well as the main topics under analysis and types of documents/sources used to publish studies of SIEs.

Methodology
In order to analyze the problematics associated with self-initiated expatriation (namely, when it started to be studied, who has published in this area of research, and what the main types/sources of publication and main topics that have been studied are), a qualitative, exploratory, and descriptive study of an interpretive nature was carried out with the support of bibliometric analysis.Of great relevance to studies of this nature is bibliometric analysis, through which it is possible to identify, among other observations, the number of documents produced on a given subject, the dates of their publication, the authors, institutions and countries that published them, the types/sources of publication and the keywords and subjects that were studied.In particular, according to Bryman and Bell (2007), the central focus of bibliometrics is to capture the state of a given field of knowledge through the analysis of old and recent works.In this analysis, the Scopus database (from Elsevier), considered one of the most important and reputed databases in the context of scientific production, was used as a research tool.In order to achieve the proposed objectives, a documentary search was carried out using the Scopus database (duly authorized) during the month of August 2022, according to the following procedure: 1.
In a first step, in order to contextualize the theme of expatriation (a global concept that incorporates the self-initiated expatriation concept), a search was carried out based on the keyword 'expatriation', more specifically (TITLE-ABS-KEY expatriation).2.
In this first stage of research, covering the period from 1833 to 2022 (August), without any restrictions as to the types of documents concerned, 1050 documents were identified.

3.
After carrying out a brief analysis of these results (contextualizing the research in terms of expatriation) and verifying the relevance of the problem of self-initiated expatriation within in the sphere of expatriation, the focus of the analysis began to concentrate on this latter concept.In this way, we sought to develop a specific analysis of self-initiated expatriation/self-initiated expatriates.4.
Thus, in a second step, a new search was carried out based on the keyword 'self-initiated expatriation', or more specifically (TITLE-ABS-KEY {self-initiated expatriation}).5.
In this second stage of research, covering the period from 2010 to 2022 (August), without any restrictions as to the types of documents concerned, 82 documents were identified.6.
These 82 documents became the target of the analysis carried out, through which we sought to answer the central questions of this article.

Results Analysis and Discussion
Based on the SCOPUS database, using the term "expatriation"-which, in its traditional sense, refers to a mission abroad for a certain period of time by an organization's employee-as a keyword, 1050 documents were identified.In perfect harmony with the observations discussed at the beginning of this article, i.e., the notion that there have always been cross-border displacements of individuals, it was quickly observed that the first of these documents dated from 1833.Published in the American Journal of the Medical Sciences by James Johnson (1833), the importance and impact of overseas travel was the focus of this document, with some emphasis on voluntary expatriation.After this first publication, following a period of about 130 years in which there were no publications on this area of research, from 1963 onwards, although in very small numbers, publications began to appear focusing on the problem of expatriation.However, it was from the 1990s onwards that publications focusing on expatriation began to take on greater importance.This is largely due to the fact that, from this decade onwards, with the opening of markets, the growing discussions on globalization and the internationalization of companies and individuals, the concept of international human resource management and, with it, the concept of expatriation began to assume greater relevance.As mentioned by Pinnington and Harzing (2015), even if it is true that, from this decade onwards, the concept of IHRM became more straightforward due to technological evolution, it is also true that it also Adm. Sci.2022, 12, 136 5 of 17 became more complex as a result of the increasing levels of qualification required and the different forms of the regulation of global business.
However, if the 1990s constituted the turning point of publications focusing on expatriation, as can be seen from the analysis in Figure 1, it was with the turn of the millennium that studies in this field of research began to intensify.This is largely due to the fact that, from this decade onwards, with the opening of markets, the growing discussions on globalization and the internationalization of companies and individuals, the concept of international human resource management and, with it, the concept of expatriation began to assume greater relevance.As mentioned by Pinnington and Harzing (2015), even if it is true that, from this decade onwards, the concept of IHRM became more straightforward due to technological evolution, it is also true that it also became more complex as a result of the increasing levels of qualification required and the different forms of the regulation of global business.
However, if the 1990s constituted the turning point of publications focusing on expatriation, as can be seen from the analysis in Figure 1, it was with the turn of the millennium that studies in this field of research began to intensify.Analyzing the contents of these documents, it can be observed that, since expatriation is the focus of the analysis, the problem of SIE has already assumed particular relevance, as mentioned by Al Ariss and Crowley-Henry (2013).Highlighting just some of the most recent publications, it can be observed that Jiang et al. (2022), aware of the challenges of mobility arising from globalization, in their study of expatriation sought to place particular emphasis on the ways in which the SIE defines the "self" and the "place" through the processes of expatriation and individual career development.Maharjan et al. (2022), in turn, focusing on academic expatriation, sought to study the research productivity of academic SIEs in terms of their performance and integral parts of their work.Rosa González et al. (2022), examining the issue of COVID-19 and SIE, studied the pandemic's effects on the expatriation experience of Spanish SIE nurses in Germany in order to assess the differences in terms of their feelings of security by comparing the countries of origin and the host countries.In this way, they assessed the impacts of this factor on the length of stay in the host country or interest in repatriation to their country of origin.Cho and Chew (2021) studied expatriation by exploring the issue of the work-life balance of SIEs.Analyzing the contents of these documents, it can be observed that, since expatriation is the focus of the analysis, the problem of SIE has already assumed particular relevance, as mentioned by Al Ariss and Crowley-Henry (2013).Highlighting just some of the most recent publications, it can be observed that Jiang et al. (2022), aware of the challenges of mobility arising from globalization, in their study of expatriation sought to place particular emphasis on the ways in which the SIE defines the "self" and the "place" through the processes of expatriation and individual career development.Maharjan et al. (2022), in turn, focusing on academic expatriation, sought to study the research productivity of academic SIEs in terms of their performance and integral parts of their work.Rosa González et al. (2022), examining the issue of COVID-19 and SIE, studied the pandemic's effects on the expatriation experience of Spanish SIE nurses in Germany in order to assess the differences in terms of their feelings of security by comparing the countries of origin and the host countries.In this way, they assessed the impacts of this factor on the length of stay in the host country or interest in repatriation to their country of origin.Cho and Chew (2021) studied expatriation by exploring the issue of the work-life balance of SIEs.
These brief examples are good indicators of the relevance that the subject of SIEs has come to assume in the context of expatriation.In this sense, in order to meet the proposed objectives, what can be said about the reality of publications focusing on SIE?
Aware of the importance that SIEs have assumed in the overseas labor markets (as mentioned by Jokinen et al. 2008), we sought to carry out a more exhaustive analysis of the scientific production of this field of research.To this end, using the keyword "selfinitiated expatriation", 82 documents were identified in the Scopus database that specifically focus on studies addressing the topic SIE.As mentioned above, despite the fact that the issue of expatriation has been widely studied by several researchers for many years, according to the data collected, it was only from 2010 onwards that the topic of SIE began to gain more evidence (Figure 5).These brief examples are good indicators of the relevance that the subject of SIEs has come to assume in the context of expatriation.In this sense, in order to meet the proposed objectives, what can be said about the reality of publications focusing on SIE?
Aware of the importance that SIEs have assumed in the overseas labor markets (as mentioned by Jokinen et al. 2008), we sought to carry out a more exhaustive analysis of the scientific production of this field of research.To this end, using the keyword "self-initiated expatriation", 82 documents were identified in the Scopus database that specifically focus on studies addressing the topic SIE.As mentioned above, despite the fact that the issue of expatriation has been widely studied by several researchers for many years, according to the data collected, it was only from 2010 onwards that the topic of SIE began to gain more evidence (Figure 5).
The analysis in Figure 5 allows us to observe that, while the most recent decade was the most fruitful in terms of publications related to SIE, it was the period between 2012 and 2014 that produced the largest number of published documents.An explanation for this may be the fact that, as the years preceding this period were characterized by a profound economic and financial crisis, with profound repercussions for the different labor markets and society in general, the motivations of individuals to gain international mobility have taken on more accentuated contours, which may have led researchers to study the phenomenon of SIE.In the same line of thought, we must emphasize that the events that have been observed in recent times (the war, the search for safer countries and the impending new economic and financial crisis) have given rise to higher levels of mobility, with impacts on the labor market.Since this is a favorable scenario for the development of studies on these migratory movements, it is expected that, in the coming years, the number of publications on the subject of SIE will increase.The analysis in Figure 5 allows us to observe that, while the most recent decade was the most fruitful in terms of publications related to SIE, it was the period between 2012 and 2014 that produced the largest number of published documents.An explanation for this may be the fact that, as the years preceding this period were characterized by a profound economic and financial crisis, with profound repercussions for the different labor markets and society in general, the motivations of individuals to gain international mobility have taken on more accentuated contours, which may have led researchers to study the phenomenon of SIE.In the same line of thought, we must emphasize that the events that have been observed in recent times (the war, the search for safer countries and the impending new economic and financial crisis) have given rise to higher levels of mobility, with impacts on the labor market.Since this is a favorable scenario for the development of studies on these migratory movements, it is expected that, in the coming years, the number of publications on the subject of SIE will increase.
Focusing our attention on the documents published by each author, it can be observed that, as the top five authors who have published the most on this issue, one can highlight Vesa Suutari (8 published documents), Maike Andresen and Noeleen Doherty (with 7 documents each), as well as Chris Brewster and Kaye Thorn (with 6 documents each) (Figure 6).Focusing our attention on the documents published by each author, it can be observed that, as the top five authors who have published the most on this issue, one can highlight Vesa Suutari (8 published documents), Maike Andresen and Noeleen Doherty (with 7 documents each), as well as Chris Brewster and Kaye Thorn (with 6 documents each) (Figure 6).Within the scope of SIE, Vesa Suutari has published on topics related to the existing literature on SIEs, the proposal of a research agenda (Brewster et al. 2021;Dorsch et al. 2012), career issues (Mello et al. 2020;Dickmann et al. 2018;Al Ariss et al. 2012, 2013) and issues related to the recognition of space, time and institutions (Andresen et al. 2020a(Andresen et al. , 2020b)).
Maike Andresen, in turn, pays particular attention to issues related to the concept of self-initiated expatriation (Andresen et al. 2020c), the recognition of space, time and institutions (Andresen et al. 2020a(Andresen et al. , 2020b) and the differences between self-initiated expatriation and assigned expatriation (Andresen et al. 2014(Andresen et al. , 2015)), as well as the individual, organizational and national perspectives on self-initiated expatriation (Andresen et al. 2012a(Andresen et al. , 2012b)).
Noeleen Doherty seeks to highlight the gender issue of self-initiated expatriation (Myers et al. 2022;Doherty and Thorn 2014), while also paying attention to the career issue (Doherty et al. 2013a;Doherty and Dickmann 2012) and the motivations to go abroad (Doherty et al. 2011) and seeking to contribute to a better clarification of the SIE concept (Doherty 2013;Doherty et al. 2013b).
In close relationship with Vesa Suutari, Chris Brewster, in his work, also highlights topics related to the existing literature on SIEs and the proposal of a research agenda (Brewster et al. 2021;Dorsch et al. 2012), as well as career issues (Mello et al. 2020;Dickmann et al. 2018) and issues related to the recognition of space, time and institutions (Andresen et al. 2020a(Andresen et al. , 2020b)).
Still within the top five main authors, Kaye Thorn (in association with Noeleen Doherty) also pays particular attention to the gender issue of self-initiated expatriation (Myers et al. 2022;Doherty and Thorn 2014) and career issues (Doherty et al. 2013a), as well as a better clarification of the SIE concept (Doherty et al. 2013b).Issues related to the repatriation of SIEs (Ellis et al. 2020) and the problem of talent (Thorn and Inkson 2012) have also been studied by this author.
It should be emphasized that, even though they are individual researchers, most of the authors mentioned here have developed several works together.Many of the articles analyzed are, therefore, common to several of them.
Observing the types of documents that have been published most frequently, it can be observed that articles are more prominent, with a weight of 69.5% of the total publications (which corresponds to 57 documents in Scopus), followed by book chapters (19.5% of publications, corresponding to 16 documents) (Figure 7).Observing the types of documents that have been published most frequently, it can be observed that articles are more prominent, with a weight of 69.5% of the total publications (which corresponds to 57 documents in Scopus), followed by book chapters (19.5% of publications, corresponding to 16 documents) (Figure 7).With regard to the sources of the articles on SIE, the International Journal of Human Resource Management (14 articles) and Journal of Global Mobility (14 articles), followed very closely by Career Development International (10 articles), are the journals that have produced With regard to the sources of the articles on SIE, the International Journal of Human Resource Management (14 articles) and Journal of Global Mobility (14 articles), followed very closely by Career Development International (10 articles), are the journals that have produced the highest number of publications on this topic of research (Figure 8).With regard to the sources of the articles on SIE, the International Journal of Human Resource Management (14 articles) and Journal of Global Mobility (14 articles), followed very closely by Career Development International (10 articles), are the journals that have produced the highest number of publications on this topic of research (Figure 8).It is important to note that, despite the fact that the International Journal of Human Resource Management and Journal of Global Mobility are the two journals among the top five sources with the most publications on SIE, IJHRM is assumed to be a major reference work It is important to note that, despite the fact that the International Journal of Human Resource Management and Journal of Global Mobility are the two journals among the top five sources with the most publications on SIE, IJHRM is assumed to be a major reference work in the field of studies on human resources in an international context, as reflected by the greater number of citations attributed to it (Figure 9).
With the study of SIE as its central focus, reinforcing the main themes developed by the top five authors who have been most active in this field of research (already mentioned above), one can observe that the research that has been developed in this field has adopted different approaches.Nolan and Liang (2022), for instance, draw attention to the fact that, despite their high levels of mobility, little research has been conducted on medical doctors with respect to this subject.In particular, these authors seek to study the determinants of cross-border adjustment among self-initiated medical doctors who work and live in host countries.Myers et al. (2022), in turn, sought to highlight the issue of gender in self-initiated expatriation.In particular, these authors, through the investigation of older women, sought to study the motivations of SIEs in terms of their personal and career motivations.Purgał-Popiela (2021) focused her analysis on the definition of the role of non-traditional expatriation in global talent management.She sought to explore the ways in which particular forms of global mobility (such as self-initiated expatriation) contribute to global talent management and to identify the key underlying challenges.Brewster et al. (2021) studied the literature published in the field of SIE during the last twenty years in order to analyze what we know about this issue and propose a research agenda.This study allowed the authors to highlight the main research topics, as well as the knowledge gaps, in the field of SIE over the last two decades and, in this way, define avenues for future research.Emphasizing that the various analyses of SIE focus more on expatriation than on repatriation itself, Ellis et al. (2020) sought to study how repatriated SIEs perceive their repatriation experience compared to their expectations of their return.Andresen et al. (2020c), highlighting the importance of personal initiative as a critical behavior determining the ability to acquire future jobs, focused their study on the analysis of the personal initiative characteristics of SIEs, emphasizing that initiative is very context-dependent, while proposing methods of measuring this initiative.Placing particular emphasis on Portuguese emerging adult SIEs, Farcas and Gonçalves (2019) carried out a study based on a model of cross-cultural adaptation.Additionally, focusing on the process of adjustment to international work environments, Agha-Alikhani ( 2018) focused her analysis on self-initiated academics, drawing attention to the perception and perceived relevance of adjustment processes in an academic context.Focusing on crossborder careers, particularly career competencies, Dickmann et al. (2018), in a comparison between self-initiated expatriates and assigned expatriates, concluded that, with respect to different dimensions of career capital, expatriates learn more than self-initiated expatriates.
Adm. Sci. 2022, 12, x FOR PEER REVIEW 11 of 17 in the field of studies on human resources in an international context, as reflected by the greater number of citations attributed to it (Figure 9).With the study of SIE as its central focus, reinforcing the main themes developed by the top five authors who have been most active in this field of research (already mentioned above), one can observe that the research that has been developed in this field has adopted different approaches.Nolan and Liang (2022), for instance, draw attention to the fact that, despite their high levels of mobility, little research has been conducted on medical doctors with respect to this subject.In particular, these authors seek to study the determinants of cross-border adjustment among self-initiated medical doctors who work and live in host countries.Myers et al. (2022), in turn, sought to highlight the issue of gender in self-initiated expatriation.In particular, these authors, through the investigation of older women, sought to study the motivations of SIEs in terms of their personal and career motivations.From the analysis carried out on the approaches of some of the most recent studies that have been conducted on the topic of self-initiated expatriation, we can observe that these fundamentally fall within the area of business and management.This evidence is perfectly reflected in the data acquired from Scopus, through which it is possible to observe that, analyzing the documents by subject area, the business, management and accounting area is the one with the most published documents (out of a total of 78 documents in Scopus, corresponding to 61.9% of publications in this area), followed by the area of economics, econometrics and finance (with 20 documents, corresponding to 15.9%) and the area of the social sciences (with a weight of 14.3%, corresponding to 18 published documents) (Figure 10).
counting area is the one with the most published documents (out of a total of 78 documents in Scopus, corresponding to 61.9% of publications in this area), followed by the area of economics, econometrics and finance (with 20 documents, corresponding to 15.9%) and the area of the social sciences (with a weight of 14.3%, corresponding to 18 published documents) (Figure 10).Given that some subject areas can cross over one another, it is possible that the same article accounts for more than one subject area.
In concluding this analysis, it is important to highlight the origins of the main studies that have been conducted in this area.Based on the top five countries of origin of the main studies and consequently, of the main publications on the topic of self-initiated expatriation, it can be observed that the United Kingdom (with 34 documents), France (15 documents), the United States (14 documents), Germany (13 documents) and Australia (8 documents), along with Canada, Finland and New Zealand (all with 8 documents), are the countries where the numbers of works published in the area of SIE are highest (Figure 11).Given that some subject areas can cross over one another, it is possible that the same article accounts for more than one subject area.
In concluding this analysis, it is important to highlight the origins of the main studies that have been conducted in this area.Based on the top five countries of origin of the main studies and consequently, of the main publications on the topic of self-initiated expatriation, it can be observed that the United Kingdom (with 34 documents), France (15 documents), the United States (14 documents), Germany (13 documents) and Australia (8 documents), along with Canada, Finland and New Zealand (all with 8 documents), are the countries where the numbers of works published in the area of SIE are highest (Figure 11).These geographic locations are in perfect harmony with the affiliation of the main authors of these works, insofar as there is an adequate correspondence between the countries where these works originate from and the institutions that the authors belong to, These geographic locations are in perfect harmony with the affiliation of the main authors of these works, insofar as there is an adequate correspondence between the countries where these works originate from and the institutions that the authors belong to, with eight publications from Cranfield University (United Kingdom), Vaasan Yliopisto (Finland), Universitat Bamberg (Germany) and Cranfield School of Management (United Kingdom); six documents from the University of Reading (United Kingdom) and Henley Business School (United Kingdom); and five documents York University (Canada) and the TBS Business School (France) (Figure 12).These geographic locations are in perfect harmony with the affiliation of the main authors of these works, insofar as there is an adequate correspondence between the countries where these works originate from and the institutions that the authors belong to, with eight publications from Cranfield University (United Kingdom), Vaasan Yliopisto (Finland), Universitat Bamberg (Germany) and Cranfield School of Management (United Kingdom); six documents from the University of Reading (United Kingdom) and Henley Business School (United Kingdom); and five documents York University (Canada) and the TBS Business School (France) (Figure 12).Here, too, it is important to emphasize that, for an article to be counted among the production of a given country, at least one of the authors must be associated with an institution (educational or research) in that country.In this sense, it is possible for the same article to account for more than one country or institution.
Having analyzed and discussed the main data obtained, in order to answer the central questions of this article, it can be stated that, with regard to publications within the scope of SIE and the question of "when the problem of SIE started to be studied", although the issue of expatriation, in its traditional sense, has been the subject of analysis and discussion for many years (gaining greater attention from the 1990s onwards), the works with a specific focus on self-initiated expatriation only emerged as a particular target of study from 2010, with scientific articles being the main typology of published documents.In answer to the question "what are the main types of publication used to disseminate the works that have been developed?",it can be observed that, despite the diversity of possible options, articles (assuming a weight of 69.5 % of the documents published) constitute the main vehicle for disseminating and transmitting knowledge concerning SIE.It should be noted that, within the range of journals that publish on this issue, the International Journal of Human Resource Management (first among the top five journals with the highest number of citations), Journal of Global Mobility and Career Development International assume greater emphasis.With a large percentage of studies focused on the area of business and management (61.9%), with regard to the question "which are the main topics within the scope of SIE that have been studied?", it can be observed that the publications focusing on SIE have highlighted the most critical aspects of the management of this type of employees.These include the gender issue associated with SIEs (Myers et al. 2022;Doherty and Thorn 2014), the motivations that lead these people to move across borders (Doherty et al. 2011), the adjustment of SIEs across borders (Nolan and Liang 2022;Agha-Alikhani 2018), career competencies and talent management (Dickmann et al. 2018;Purgał-Popiela 2021;Thorn and Inkson 2012), the repatriation of SIES (Ellis et al. 2020), the issues related to personal initiative (Andresen et al. 2020c) and cross-border careers (Mello et al. 2020;Dickmann et al. 2018;Al Ariss et al. 2012, 2013;Doherty et al. 2013a), among other topics.As experts in the field of expatriation with a particular emphasis on SIE, the authors (top five) who have published the most in this field of research were identified, thus answering the question "who has published in this area of research?"In perfect harmony with the origins and affiliations of the main authors who have published the most on the topic of SIE, the top five countries and institutions producing the highest numbers of publications in the area of SIE were also highlighted, including the United Kingdom (Cranfield University, Cranfield School of Management, University of Reading, Henley Business School), Germany (Universitat Bamberg) and France (TBS Business School).

Conclusions
As a final remark, it is important to highlight that, focusing on the issue of expatriation, specifically self-initiated expatriation, in recent years, largely as a result of the challenges and changes that have been observed in different countries, the number of studies and, consequently, the number of publications have started to become significant.In this sense, in order to better understand the reality underlying this research area, the key questions that guided the structure of this article were answered throughout, namely: "when did the problem of SIE start to be studied?","who has published in this area of research?","what are the main types of publication used to disseminate the works that have been developed?",and "which are the main topics within the scope of SIE that have been studied?" The results obtained allowed us, among other observations, to conclude that although the phenomenon of expatriation has been studied for many years, the particular case of SIE started to gain greater prominence from 2010 onwards, with the highest peak in publications observed in the period between 2012 and 2014.The top five main authors who are working in this field, the main sources of these publications (mostly scientific articles), the main countries of origin and the main approaches developed and studied by the different authors were highlighted here.
From the theoretical point of view, this study is particularly relevant, as it contributes to a greater awareness of SIE, providing, at the same time, a greater level of knowledge regarding the concept itself, as well as information about the topics that have been studied and by whom, over what length of time and in which countries or territories, as well as the main sources of the dissemination of different studies.
From a practical point of view, as a reality that is increasingly felt in different cultures as a result of the growing processes of mobilization and displacement across borders through the initiative of individuals, the existence of self-initiated expatriates requires the organizations that host them to ensure the promotion and development of adjustment policies in the context of different organizational realities.More specifically, particularly with regard to the political implications of this study, it is of great importance to encourage the development of more exhaustive studies of SIE, thus contributing to the promotion of policies and practices oriented towards the management of SIE, enabling us to exploring the potential skills that these individuals have more deeply and thus contributing to the greater and more effective development of the companies and economies of the countries that host them.Given that, thus far (to the best of our knowledge), there are no publications answering the questions addressed in this article, its added value lies in the fact that it provides a systematization of the research that has been conducted in this area.From now on, with access to knowledge regarding who is active in this field of study, what research has been conducted, how and where the obtained results are disseminated and the origins of the studies (country/territory and affiliation), future researchers will find a relevant starting point for their own research in this study.Knowing who the main authors are and what topics they study, for example, helps researchers to orient their research based on the authors and topics that interest them most at an early stage.
Having explored the field of research on SIE, we intend, in future work, to carry out a meta-analysis using statistical techniques that will allow us to integrate the results of different independent studies, while focusing on the same research question, thus combining the results.

Figure 1 .
Figure 1.Expatriation documents by year.Source: Data obtained from Scopus (August 2022).With the publications Chris Brewster (29 documents), VesaSuutari (25), MichaelDickmann (20), Susan Shortland (17)  and Yvonne McNulty (15), as the top five authors who have published the most in this area (Figure2), the data obtained also allow us to conclude that articles are the most frequently published type of document (with a weight of 75.4% of the publications, corresponding to 793 documents in Scopus) (Figure3).With respect to the sources, the International Journal of Human Resource Management (112 documents), Journal of Global Mobility (83), Career Development International (26), Journal of World Business (17) and Human Resource Management (13 documents) are the top five the journals that have published the most on expatriation (Figure4).Analyzing the contents of these documents, it can be observed that, since expatriation is the focus of the analysis, the problem of SIE has already assumed particular relevance, as mentioned by Al Ariss and Crowley-Henry (2013).Highlighting just some of the most recent publications, it can be observed thatJiang et al. (2022), aware of the challenges of mobility arising from globalization, in their study of expatriation sought to place particular emphasis on the ways in which the SIE defines the "self" and the "place" through the processes of expatriation and individual career development.Maharjan et al. (2022), in turn, focusing on academic expatriation, sought to study the research productivity of academic SIEs in terms of their performance and integral parts of their work.RosaGonzález et al. (2022), examining the issue of COVID-19 and SIE, studied the pandemic's effects on the expatriation experience of Spanish SIE nurses in Germany in order to assess the differences in terms of their feelings of security by comparing the countries of origin and the host countries.In this way, they assessed the impacts of this factor on the length of stay in the host country or interest in repatriation to their country of origin.Cho and Chew (2021) studied expatriation by exploring the issue of the work-life balance of SIEs.

Figure 8 .
Figure 8. Self-initiated expatriation documents per year by source.Source: Data obtained from Scopus (August 2022).

Figure 8 .
Figure 8. Self-initiated expatriation documents per year by source.Source: Data obtained from Scopus (August 2022).
Purgał-Popiela (2021) focused her analysis on the definition of the role of non-traditional expatriation in global talent management.She sought to explore the ways in which particular forms of global mobility (such as self-initiated expatriation) contribute to global talent management and to identify the key underlying challenges.Brewster et al. (2021) studied the literature published in the field of SIE during the last twenty years in order to analyze what we know about this issue and propose a research agenda.This study allowed the authors to highlight the main research topics, as well as the knowledge gaps,

Figure 11 .
Figure 11.Self-initiated expatriation documents by country or territory.Source: Data obtained from Scopus (August 2022).

Figure 11 .
Figure 11.Self-initiated expatriation documents by country or territory.Source: Data obtained from Scopus (August 2022).

Figure 11 .
Figure 11.Self-initiated expatriation documents by country or territory.Source: Data obtained from Scopus (August 2022).