Theoretic insights on the concept of internal fit of HR elements within the construct of high performance work system

ABSTRACT The ‘system perspective’ concept has intensely been supported by strategic human resource management researchers , who have so far been fairly successful in producing substantial evidence to prove that synergistic and mutually reinforcing human resource (HR) practices bonded together in ‘bundles’ , can significantly affect the performance of organizations at multiple-levels . To understand how HR activities interrelate to generate positive (negative) synergistic effects and affect performance across multiple levels, it is necessary to comprehend the pattern of relationships within HR activities. However, limited efforts have been made to explore the nature of the ‘Internal-Fit’of HR elements within the construct of HPWS. This research study aims (1) to develop a multi-leveltheoretical framework of HPWS to illustrate how aligned and interrelated HR activities can generate synergistic effects that may affect performance at multiple levels and (2) to clarify the nature of ‘Internal-Fit’ of HR elements in both horizontal and vertical dimensions within HPWS.


Introduction
Human Resource (HR) experts all over the globe strongly support the notion of 'bundles' of HR practices and prefer them over individual practices while exploring the relationship of HR practices with organizational outcomes (Huselid, 1995;Macduffie, 2016). As argued by various researcher like Lado and Wilson (1994), P. Wright and Boswell (2002), Pak and Kim (2018), and Rehmani et al. (2020a). HR practices are more effective once applied in dynamic bundles/sets of individual practices, as they work well in synergistic and mutually reinforcing combinations. This concept has largely been supported by numerous theoretical and empirical studies and has attracted many researchers to intensely focus the 'system perspective' while evaluating the effect of HR practices on organizational performance (Shin & Konrad, 2017). Based on this notion, the HPWS has received widespread attention over the past few decades and can be described as 'a dynamic system of integrated or collective HR practices, policies, and processes articulated systematically to acquire and enhance the knowledge, skills, abilities commitment, opportunities and motivation of employees in pursuit of long-lasting organizational success' (Takeuchi et al., 2009). Even with the evolving consensus on the system perspective, there still remains various ambiguities and challenges related to the HPWS construct: (1) significant variations can be observed in the literature regarding the number and composition of HPWS practices, which makes it difficult to operationalize HPWS construct appropriately for analysis (Wright et al., 1994) (2) lack of understanding regarding the nature of internal-relationships among key components of HPWS. Though researchers like Schuler and Jackson (1987), Delery (1998), Lepak and Snell (2016), and Jiang et al. (2012) have generally observed these relationships, yet research is scarce regarding the in-depth examination of these internal relationships (Jiang et al., 2012). Nevertheless, few empirical studies, like one conducted by Kepes et al. (2009) have noted the interaction effects among different HR elements in isolation. Such fragmentary bivariate interactions are disjointed and inadequate without a comprehensive framework and fail to explain how the internal components of HPWS operate (3) the causal chain between HPWS elements and performance at multilevel remains to be understood explicitly (4) the concept of bi-dimensional 'Internal-Fit' of HR elements/activities within HPWS needs logical explanation (5) finally in strategic HRM literature, HPWS has either been operationalized as a single or a multidimensional construct, where its key elements/ systems have been examined at the same level of abstraction for their potential link with performance and the concept of internal-fit generally remained neglected (Rehmani et al., 2020a). Delery (1998) described 'Internal-Fit' as the internal consistency and complementarities of HR elements" and proposed supplementary, substitutive and interactive relations among HR elements within a HPW. Unfortunately, there is a lack of theoretical explanation and empirical evidence regarding the specific nature of interrelationships of HR elements within a HPWS. Chadwick is one of the few researchers who focused on this problem in-depth and proposed three methodologies (integration, independence, and configuration) while explaining the types of relationships in the HR system applicable to HPWS synergy. Given this, the first challenge while developing a conceptual framework is identifying the most relevant HR components of HPWS and classifying them in their respective levels of abstraction (macro and micro levels). The second is to explore the types and nature of inter-relationships among various HR components and delineate how these elements work together to influence performance at multiple levels. The third is to apply the bi-dimensional 'internal-fit' concept of HR elements to explain how positive and negative synergistic effects can arise within a coherent and internally aligned HPWS. This paper is organized in the following manner. First, a comprehensive literature review is carried to explore some of the significant theoretical perspectives like Resource-Based View (RBV), Behavioral and Social-Psychology perspective regarding their link with HPWS. Second, the key components of HPWS are first identified and then classified in their respective macro and micro levels. Third, three main approaches (Universalistic, Contingency, and Configurational) of strategic HRM are described to explain how different HR activities can influence organizational performance. Fourth, different types of relationships among HR elements (additive, substitutive, positive synergistic and negative synergistic) are explored. Fifth, a multilevel conceptual framework of HPWS is developed to explain the nature of inter-relationships of HR components and their potential link with a performance at multiple levels. Sixth, the concept of bi-dimensional 'internal-fit' is applied to the proposed framework to elucidate the types of horizontal and vertical fit among HR elements. Finally, implications, limitations and suggestion for future research are offered.

Theoretical background
A comprehensive review of literature has been carried out to clarify the four significant aspects related to the development of subsequent theoretical framework including (1) The universalistic, contingency, and configurational approaches within a HPWS (2) Resource-Based View, Behavioral and Social-Psychology perspective (3) AMO framework and its 'Macro' and 'Micro' level systems (4) Types of relationships among HR activities within HPWS.

The universalistic, contingency, and configurational approaches
The notion of a significant and positive influence of HPWS on firm outcomes have already been established in various research studies using different perspectives. However, the primary resolution is to find out 'how' a set of HR practices within the umbrella of HPWS affect organizational performance (B. Zhang & Morris, 2014). Strategic HRM researchers have adopted multiple approaches to seek the right answer and use the correct approach while handling this issue. Three different perspectives are well known and widely used in literature (1) Universalistic Approach argues that specific universally applicable HR practices can be applied (individually), irrespective of any particular organization or strategy, to acquire improved outcomes. For instance, Boxall and Macky argued that regardless of organization or approach applied, enhanced organizational outcomes could be attained by using a specific sequence of universal HR practices, which works well in all conditions and scenarios. Nevertheless, the universalistic approach cannot explain how HR activities could be a persistent resource for organizational performance in a sustainable manner (Ployhart, 2012). For example, Huselid (1995) studies the impact of HPWS on organizational performance and strongly advocated that HPWS have a significant positive effect on employee turnover, firm's output, and business outcomes for small, medium and large size organizations belonging to different industries and setups. (2) Contingency Approach; introduces the notion of 'contextual factors' while examining the causal link between HR activities and organizational outcomes. It strongly accentuates the significance of an 'external or vertical fit,' i.e. aligning HR elements with external contingencies (e.g. market condition, unionization, business strategy etc.) (Lengnick-Hall et al., 2009). Although this perspective is significant in many ways and conditions, it fails to consider the inter-relationship between HR elements within a HPWS. (3) Configuration Approach suggests that HPWS construct is an integrated system of interrelated HR elements/activities (Macduffie, 2016) such that the effectiveness of all HR element is significantly dependent upon each other. It further advocates that if there is a corresponding match between multiple levels of the organization and distinct HR architecture, it will strongly support organization practices and HR systems (Posthuma et al., 2013). The configurational approach, which focuses on how 'patterns' of HRM practices (rather than discrete activities) are applied to dependent variables, is of concern. HRM is seen as a unified framework. It is believed that the company will accomplish its objectives by a unique mix of HR activities. As advocated by researchers like Ananthram et al. (2018), Nyberg et al. (2016), and Schmidt and Keil (2013), HRM activities can be a strategic resource for a sustainable organizational success if they are valuable and rare as well as complex, if not impossible to imitate or substitute (Rehmani et al., 2020a). Interrelated HRM activities aligned with each other are inherently socially complex, casually ambiguous (Bowen, 2016) and could be difficult for competitors to copy (Banks & Kepes, 2015).
First, to be valuable, HR activities must generate 'value' by decreasing costs or growing revenue to produce sustainable financial outcomes. For example, an organization may adopt a new training curriculum that equips first-line supervisors with the skills they need to take on specific managerial responsibilities. As a result, the organization will reduce the number of managers required, thereby lowering labour costs. Second, although 'value' is an essential criterion, yet not adequate to achieve a sustainable competitive edge. HR practices may therefore be 'rare' to be considered a strategic resource. HRM practices that are valuable but not 'rare' will only result in relative parity, not a competitive edge (Rehmani et al., 2020a). For instance, using cognitive skill testing to screen job candidates is successful; the advantages of such tests are universal across businesses and industries In other words, while cognitive skill assessments help identify necessary human capital, they are not 'rare' since any organization may use them to hire workers (Appelbaum et al., 2000). Third, organizations are likely to achieve sustainable competitive advantage through acquiring 'valuable' and 'rare' HR activities/practices in the short run. Nevertheless, to be a vital strategic resource and produce long-term enhanced business outcomes, HR activities/practices must be difficult to imitate. A crucial strategic resource is more challenging to replicate if it can be termed causally ambiguous or socially complex (Ananthram et al., 2018;Bello-Pintado, 2015). Contrary to 'best practices' (i.e. the universalistic perspective) and HR practices within a particular context (e.g. the contingency perspective), interrelated HR practices are a resource that can lead to a sustainable organizational performance (Kehoe & Wright, 2013;Z. Zhang & Jia, 2010).

Resource-based view, behavioral and social-psychology perspective vis-à-vis HPWS
According to the resource-based view, the 'configurational perspective' can be used to explain why HRM practices may serve as a resource for a sustainable organizational performance (Bui et al., 2016;Campbell et al., 2012).
The concept that various HR practices can influence organizational performance is strongly linked with the RBV that inspires employers to ascertain essential resources required to achieve enhanced and maintainable organizational performance . Multiple theoretical perceptions and concepts have been used to elucidate how HPWSs practices influence organizational outcomes (Wright et al., 1994). As advocated by the researcher like Jiang et al. (2012), Campbell et al. (2012), and Pak and Kim (2018), RBV covertly attributes a 'system perspective' regarding HR activities in which a systematic combination of complementary HR practices results in the attainment and sustenance of competitive advantage and improved business outcomes. Thus, the RBV of the organization works as a framework for illustrating the criteria under which integrated HR elements belonging to HPWS sets a strong foundation for sustainable organizational effectiveness (Campbell et al., 2012).
Likewise, as demonstrated in various research studies (e.g. Cascio, 2006;Kanie & Biermann, 2017;Nyberg et al., 2016), the majority of causes towards negative workplace attitudes and diminished organizational performance are also related to behavioural perspectives like job layoffs, persistent and growing conflict between work and family, breakage of implicit or explicit promises by employers, inadequate compensation and reward system and non-conducive working environment etc. However, there is evidence of significant differences in HR strategies within the same market. Some firms opt for a 'high road,' commitment-based strategy that includes higher pay and job protection, while other seemingly identical companies opt for a 'low road' strategy. Furthermore, there is no evidence that businesses that take the 'low road' are more successful or profitable. Schuler and Jackson (1987) have supported the employment of 'behavioural perspectives' while explaining the significant positive impacts of HPWS through establishing an incentive equivalence within an organization and its workforce. This sets a solid foundation for the development of an AMO (Ability-Motivation-Opportunity) framework, which advocates that employees knowledge, skills, and abilities (KSAs); employees motivation and commitment; and employees opportunities to contribute are three vital elements that significantly link HPWS and employee behaviours (Bui et al., 2016). Likewise, the 'social-psychology approach' has also been used in literature to explain the cause of the significant increase of employees trust, commitment and behaviour (both in and outside work), resulting in improved business outcomes through organization's investment in its employees by implementing HPWS (Kehoe & Wright, 2013). However, it is observed that the majority of studies have preferred a unitarist perspective, which is based on the assumption that 'there is a significant alignment between organization's and employee's interests' (Z. Zhang & Jia, 2010).

The AMO framework and its 'macro' and 'micro' level systems
The perspectives like RBV, behavioural and social-psychology have laid a solid foundation for subsequent development of different frameworks of HPWS where HR activities and components are combined in specific 'bundles', 'systems', or 'configurations' and have extensively been investigated in various management studies over the last few decades (Jiang et al., 2012). Different kinds of methods, techniques, conceptualizations and philosophies have been developed for assessing the eco-system of HPWS involving numerous combinations of HR practices designed to achieve specific organizational outcomes (Jiang & Liu, 2015a;Jyoti et al., 2015). Most of the focus of empirical evidencebased studies dealing with HR combination remained on HPWSs (Pak & Kim, 2018).
Several researchers have introduced multiple ideas and combined various HR practices within HPWS to explore its potential link with employees and organizational performance (Jiang et al., 2015). Moreover, the majority of studies related to HPWS are primarily based upon the notion that HPWSs allow the organization and its workforce to attain mutual collaboration, such that, whenever organizational objectives are accomplished, employees will undoubtedly be benefited as well through improved human capital and several financial inducements (Liao et al., 2009).
Several researchers also recently presented a novel conceptualization. of human capital resources that deviates from the dominant perspective of the human capital theory that has existed for more than a few decades (Kuijken et al., 2017;Ployhart, 2012;Schmidt & Keil, 2013). As per this new perspective, human capital resources can be characterized 'as an individual or unit-level capacities based on individual KSAOs that are accessible for unit-relevant purposes' (Nyberg et al., 2016). Yet, researchers have not been able to develop a universally accepted concept that categorizes distinct HR activities into 'mandatory' or 'discretionary' bundles (Liao et al., 2009).
However, the concept of the AMO (Ability, Motivation and Opportunity) framework proposed by researchers like Subramony (2009), Bello-Pintado (2015), Rehmani et al. (2020a), and Appelbaum et al. (2000) have fairly been able to fill this gap. The AMO framework categorizes the HR activities/components into three macro-systems such that each macro-system is further divided into multiple micro-systems. Table 1 shows the details of the components of AMO bundles.
Moreover, there are difficulties in interpreting the structure of HR systems in the literature. Specifically, few efforts have been made to explicate the internal fit in HR systems, referring to how the practices in human resource systems work together. Schuler (1992) was amongst the pioneers who proposed the concept of establishing a systematic link between the HR system and strategic organizational needs by introducing the famous 5-P Model of SHRM (HR Philosophy, Policies, Programs, Practices, and Processes). However, whether these HR activities are classified as strategic or not depends on the business's strategic needs, or their long/short period, or whether they target senior Sharing Participation management rather than non-managerial workers remained ambiguous. Lepak and Snell (2016) found that macro-level HPWS influenced an individual's strategic principles of human resources. Furthermore, the importance of a particular employee's knowledge, skills, and abilities to the company is used to determine their intellectual resources (Wright et al., 1994). Likewise, scholars like Lepak and Snell (2016) have proposed that macro-level HR activities are not beneficial to all employee classes to the same extent (or in the same way).
Nevertheless, the causal chain between HR activities and organizational-level performance is not yet well understood, regardless of numerous calls for studies to explicate the interceding processes within the causal chain (Banks & Kepes, 2015). Still, an inclusive understanding of the explicit subtleties within the 'black box' has not mainly progressed since Becker et al. (1997) first presented this concept as the dominant or intermediary links between the best HR practices inputs and the subsequent output terms of organizational excellence. This is unfortunate because it is imperative to unveil the 'black box' to contemplate how and why HR activities affect employee, departmental and firm outcomes and sustainable organizational performance and competitive advantage (Rehmani et al., 2020a). At large, there is consensus on the two fundamental mediating mechanisms between HR activities and performance-based results. First, HR activities may directly affect organizational performance, for example, by developing operational efficiencies by reducing labor costs (Nyberg et al., 2016) or by enhancing the automation of services by introducing technology (Fogarassy et al., 2017). Though this mechanism can be applied to enhance individual-, departmental-, and organizational-level outcomes, it is not devoid of limitations because of several external and internal restraints. Second, HR practices can affect organizational-level results via a more multifaceted and complex causal chain linking individual-level subtleties.
This second mechanism's intricacy enables the organizations to use the internal fit of HR activities as a 'strategic resource' to achieve higher performance levels than its rivals (Banks & Kepes, 2015). The resource-based view offers the rational basis for arguing that internally aligned HR practices can serve as a strategic resource in the pursuit of sustainable organizational excellence as systems of interconnected HR activities can be valuable, rare, and "hard, if not impossible for rivals to ascertain and replicate. Nevertheless, this dynamic and complex causal pathway within the 'black box' has only been examined through a small amount of study (Banks & Kepes, 2015).
Once these systematic combinations of HR activities/components are set to establish a coherent HPWS within an organization, there are likely chances of significant improvement in its effectiveness, performance and competitive advantage. Based on this concept, numerous studies have shown that HPWS practices enhance the importance, distinctiveness, and individuality of employees' knowledge, skills, and abilities. As a result, their motivation and commitment are also positively affected by the firm's effectiveness (Shin & Konrad, 2017). Table 2 presents some of the critical studies linking HPWS with organizational outcomes.

Additive relationships
; are typically generated from HR elements having a universal positive (or negative) influence on results. For instance, using a 'cognitive ability' test during the selection procedure may positively affect employee performance together with additional selection criteria, such as work sample tests (Kepes et al., 2009). Therefore, it can be assumed that additive relationships are corresponding by nature, such that the separate effects of respective HR element can simply be summed up (1 + 1 = 2).

Substitutable (overlapping) relationships
Are observed when the combined effect of two distinct HR elements on outcomes is the same as that of the separate impact of each individual activity (Delery, 1998). Thus, it is evident that such activities can easily be substituted or replaced with each other to alleviate the need for one another or even multiple activities. Organizations can reduce cost and avoid wastage of resources through evasion of applying two redundant activities. For example, employee stock ownership and profit-sharing practices are two redundant activities that cannot be used in a combination as (1 + 1 = 1), so the organization in such cases should look for some independent HR elements.

Positive synergistic relationships
Are observed when two distinct HR elements interconnect to influence the outcome positively (Delery, 1998). Likewise, internally aligned HR elements within HPWS may generate certain positive relationships that are unlikely to achieve through any single HR element or simple additive relationship. For instance, an organization can use the combination of two activities like pay-for-performance and effective performance appraisal to establish a connection between compensation and performance to enhance employee motivation. The combination of these two is essentially required to confirm that employees get rewards as per their performance. Thus, the synergistic relationship can be achieved regarding employee compensation and performance management, boosting employee motivation and performance and enhancing unit -and departmental-level outcomes (1 + 1 > 2).

Negative synergistic relationships
Are observed when there is a significant misalignment among HR activities (Becker et al., 1997). Such as, if an organization designs jobs to boost employee collaboration to reach a shared objective, for example, a job design practice, however, rewards employees for their solo performance, thus discouraging teamwork. This type of potentially negative synergistic relationship will negatively affect the outcomes at individual-, departmental-, and organizational-level (1 + 1 < 2).

Development of conceptual framework
Based on RBV of organization, the AMO framework and its macro and micro level HR bundles, three perspectives of strategic HRM, and types of relationships among HR elements/activities, a conceptual framework is developed to explore the types and nature of inter-relationships among various HR components and to delineate how these elements can establish Internal-Fit to influence performance at multiple levels. The first step in developing this conceptual framework is to choose the most relevant 'perspective' to our conceptualization of this phenomenon. As the configurational approach primarily emphasizes the notion of 'Internal-Fit' of HR elements and have strongly been supported by the RBV of the organization, hence considered the best approach to clarify how HR elements can function as a resource for enhanced performance at multi-level of the organization . Figure 1 depicts the proposed theoretical framework.
Based on previous research studies on the nature of HR relationships and HR elements like HR philosophy, HR policies, HR practices, and HR processes (Banks & Kepes, 2015;;Jiang et al., 2012), a conceptual framework has been proposed. The key HR elements within a HPWS are categorized and investigated at two different levels of abstraction or systems, i.e. (1) 'Macro-Level System' and (2) 'Micro-Level System'. The rationale behind this is (1) to have a better understanding of the 'Inter-Fit' in horizontal and vertical dimensions among various HR elements and (2) to delineate how these elements work together to influence performance at three distinct levels (i.e. individual, departmental and organizational level) because the nature of the relationship among HR elements as well as their potential link with performance significantly varies along with these levels. The subsequent section will explain these two systems and their sub-systems.

Macro-level system
The Macro-Level system deals with two top-level elements, HR domains and their respective HR policies.

HR domains
; various researchers have strongly argued that all HR systems have a common fundamental configuration in a way that HR systems function through impelling abilities, motivation and opportunities of their workforce to perform (Jiang et al., 2012).

Figure 1 Conceptual framework of 'Internal fit' of HR elements within HPWS
According to the frameworks developed by Lepak and Snell (2016) and Jiang et al. (2012), to enhance the contribution of the workforce, HR policies should primarily be focused on promoting one of three fundamental HR domains: (1) knowledge, skills, and abilities (KSAs) domain; (2) motivation and commitment domain; and (3) opportunities to contribute domain. (Figure 1, Box-1).

The KSAs HR domain.
; is a set of those HR policies, HR practices, and HR processes, which are directly responsible for enhancing employees' proficiencies. Within the macro-level of HPWS, three basic HR policies are significantly related to this domain: recruitment policies, selection policies, and training policies.

The motivation and commitment HR domain.
; consist of those HR policies, HR practices and HR processes that are instigated to impact the motivation and commitment of employees instead of abilities throughout their work performance. Three basic HR policies are significantly linked with this domain: performance management policies, compensation policies, and incentive and rewards policies.

Opportunities to contribute HR domain.
; apart from enhancing the KSAs and motivation and commitment of employees, organizations must also scheme their work. Their KSAs and commitment can be channeled through the opportunity to contribute HR domain. This domain consists of two critical HR policies directly responsible for creating such opportunities: job design policies and involvement policies. It is pertinent to mention here that every policy contained by the three HR domains is executed via numerous HR practices and HR processes. Such as, 'training policy' is implemented through certain training practices like on-the-job training, off-the-job training, online training etc. Likewise, each practice within a policy, e.g. on-the-job training, is further materialized through multiple processes like discussion sessions, roleplaying, etc. (Figure 1, Box-2) are employment-related statements that provide guiding principles for the successful development and execution of several HR practices/processes within a HPWS (Schuler, 1992). The Policies can clarify what the HRM-related objectives that a particular organization is pursuing are. For example, concerning the 'compensation policy', an organization either can adopt 'pay-for-performance' or might rely on seniority (Kepes et al., 2009). However, policies do not explain how an organization undertakes its objectives. Hence, HR policies are usually very general and lack specificity to clarify necessary information linked with implementation. Lastly, there are varieties of implementable practices available against each HR policy. If an organization intends to execute a 'pay-for-performance' policy, it can use practices like merit pay, piece-rate systems, or stock plans.

Micro-level system
The Micro-Level system deals with two HR elements/ activities, i.e. HR practices and HR processes. (Figure 1, Box-3) consist of directly responsible activities to put HR policies into action. The prime objective of the practices is to make sure that policies are instigated as planned (Posthuma et al., 2013). Multiple practices can be utilized to implement any particular policy. Therefore, HR policies are general in relating what an organization desires to achieve, and HR practices are precise in describing how an organization wants to realize such objectives (Posthuma et al., 2013). (Figure 1, Box-4) belong to the lowest hierarchy level and depict employees' experiences and opinion regarding HR practices (Kepes et al., 2009). The effectiveness of HR policies and practices are primarily dependent upon the proper execution through HR processes because there are always anomalies between management view (official policies) and reality (ratified and applied practices) (Grant,). Unfortunately, most research work has only focused on HR policies and/or practices while neglecting the importance of HR processes (Liao et al., 2009). However, HR processes need to be considered explicitly because it is the level at which HR policies and practices are actually executed and deeply observed by employees. HRM policies, practices, and processes cannot simply be assumed as equivalent (Posthuma et al., 2013).

Individual, departmental, and organizational level outcomes
Individual-level outcomes are normally demarcated as a function of individual abilities (e.g. knowledge, skills, abilities, and other characteristics; KSAOs), motivation, and opportunity (P = f [A, M, O]) (Jyoti et al., 2015;Macduffie, 2016). Various researchers like Campbell et al. (2012) and Furlan et al. (2011) have strongly argued that individuallevel outcomes are antecedent to departmental and organizational-level outcomes. In this regard, a novel conceptualization of human capital resources has recently been introduced as a solid alternative to the human capital theory that has existed for quite a few decades (Nyberg et al., 2016). As per this new concept, human capital resources are described as 'individual or departmental-level capacities based on individual KSAOs that are available for department-relevant purposes' (Alkhazali et al., 2019). For instance, training effectiveness (departmental level outcome) is intensely affected by the degree of employees' ability to learn (Individual level outcome) and their learning-related personalities (e.g. locus of control), which are decided by the selection policy of an organization. Individual-level outcomes comprise of those activities that are advantageous for organizational level outcomes, for example, task performance and organizational citizenship behaviours (OCB) (Campbell et al., 2012), along with those that might have a potentially negative impact on organizational level outcomes and should be curtailed, like counter-productive work behaviours (CWB) (Ahmad and Schroeder, 2003) and turnover intentions (Lepak & Snell, 2016). Departmental and organizationallevel outcomes consist of departmental-level performance and overall organizational effectiveness (measured through financial and/or non-financial indicators (Posthuma et al., 2013).
As an illustration of how outcomes at the individual and departmental level are linked with organizational effectiveness (organizational level outcome), researchers like Adresi and Darun (2017) and Cunningham and Rowley (2008) have demonstrated a curvilinear relationship between employee turnover and organizational effectiveness. This implies that turnover will result in a lack of intellectual resources and a rise in the costs of attracting and hiring fresh talent. However, after turnover approaches a certain amount, the adverse consequences of turnover become decreasing in magnitude. Nonetheless, turnover is widely regarded as adverse to departmental and organizational-level results due to the possible depletion of human resources and the associated costs (Pak & Kim, 2018). This is particularly true for organizational performance, given the expense of removing staff and the resulting lack of firm-specific expertise, particularly if significant financial resources and time have been invested in developing employee human capital resources.

The concept of 'internal-fit' of HR elements within HPWS
The concept of Internal-Fit of HR elements within HPWS deals with evaluating the degree of alignment among various HR elements (Jiang et al., 2012). Various scholars have strongly advocated the benefits of congruence and synergy among HR elements with their potential effects on performance at multiple levels. However, there is little explanation available regarding bi-dimensional Internal-Fit (i.e. horizontal and vertical fit) within the framework of HPWS. Given this, in line with the configurational perspective, two particular categories of 'Internal-Fit' have been explored (1) Horizontal Fit and (2) Vertical Fit to explain how positive and negative synergistic effects can arise (both horizontally and vertically) among various HR elements within HPWS.

Horizontal-Fit among HR elements within HPWS
Based on the earlier investigation on potential relationships within HR elements of HPWS (Bello-Pintado, 2015;Macduffie, 2016), a framework of inter-relationships within and among HR domains, HR policies and HR practices/processes of HPWS has been conceptualized. It is proposed that all four types of relationships (additive, substitutable, positive synergistic and negative synergistic) exist within HPWS in anticipated patterns. The inter-relationships among various components of HPWS are determined through the nature of goals at multiple levels of HPWS. At the top level, the instant and direct goal of HPWS is to acquire enhanced organizational performance. For a successful accomplishment of this goal, the three HR policy domains need to influence employees KSAs, employee's motivation and commitment, and employee's opportunities to contribute. Each HR policy domain's purpose is to affect one of the three components of performance. At a more basic level, an HR policy domain's aim may have two or more sub goals that can be achieved by HR policies within that domain. For instance, an organization's KSAs HR policy domain aim may be to increase both general and particular KSAs of workforce. As a result, this goal to enhance both general and particular KSAs might become the HR policies objectives within this KSAs HR policy domain (e.g. selection policy and training policy). Likewise, at the micro level, particular HR practices are utilized to accomplish the HR policies sub-goals. The consideration of HR system goals at various levels offers a theoretical foundation for explaining the potential inter-relations among HR system components. The fundamental logic that underpins the subsequent arguments is based on the claim that collective performance at unit, departmental and organizational level is a function of employee's KSAs, employee's motivation and commitment, and employee's opportunities to contribute (Jiang & Liu, 2015a;Jyoti et al., 2015;Macduffie, 2016). Three variants of Horizontal Fit have been assessed to explain the horizontal relationships among (1) HR domains, (2) HR Policies, (3) HR Practices/ HR Processes.

Horizontal fit among HR domains.
; starting this with a psychological argument advocated by various researchers, individual performance of employees is significantly dependent upon their abilities and efforts (Gerhart, 2007;Jiang et al., 2012). Employees with strong KSAs will only perform well if they have enough motivation to exert their talents and exercise discretionary energy (P.M. Wright & Snell, 1998). On the other hand, motivated employees without the essential KSAs will not attain maximum contributions. HPWS enhances the employee's performance through the simultaneous development of abilities and commitment (Rehmani et al., 2020a). The conceptualization of integrated efforts by the workforce is also dependent upon employees' empowerment. Employees with strong KSAs and motivation will not add value until they lack fair opportunities to use their talents. On the contrary, similar employees with good opportunities to contribute can completely exploit their KSAs and motivational strength (Gerhart, 2007;Rehmani et al., 2020a). Based on these logical arguments and the synergy perspective regarding the key components of organizational performance, three HR domains are expected to operate synergistically, either positively or negatively. Suppose these three domains can achieve a perfect horizontal alignment. In that case, it is expected to have a positive synergistic relationship among them, which would eventually lead to improved organizational performance or vice versa. The second rationale in support of synergistic relationship, instead of additive or substitutive relationship among HR domains, is also based on the concept that HR domains have interdependent effects on organizational performance, as these domains emphasize three essential and interactive elements of collective organizational performance (KSAs, motivation and commitment, and opportunities to contribute). (Figure 1, Box-1)

Horizontal fit among HR policies.
; the second variant of the horizontal fit within HPWS explains the inter-relationships of HR policies inside a specific HR policy domain. All three possible combinations, i.e. additive, substitutive or synergistic, would be considered one by one. (1) The goal/objective of a particular HR policy domain is related to only 'one element' of organizational performance. For example, the goal of the KSAs domain is to improve employees' knowledge, skills, and abilities. To achieve this goal, each HR domain uses different independent policies. Each independent HR Policy would probably exert a unique effect on the goal of that particular HR domain. This unique effect is not dependent on the presence of other policies of the same HR domain. Moreover, the absence of one policy will not essentially nullify the effect of another policy, even though it can certainly reduce the net effect of the complete HR domain (Jiang et al., 2012). This argument supports the notion of the 'additive relationship' of HR policies within an HR domain (2). Given this, there is very little chance of substitutive relationships since each policy can have an exclusive influence on the goal of HR domains. (3) There is also a possibility of synergistic relationships when the nature of different policies is interdependent on the effectiveness of each other. For instance, in the KSAs HR domain, the effectiveness of training is significantly dependent on the learning ability of employees and their learning-related characters (e.g. locus of control), which are directly related to the selection policy of the organization. Therefore, to acquire highquality employees via particular selection policies, there is a need to implement a recruitment policy capable of attracting sufficient candidates for selection (Carlson et al., 2002). To conclude, it can be proposed that HR policies within an HR domain have synergistic effects on the respective element of employee performance when the goals of HR policies are interdependent; otherwise, their effects are additive. (Figure 1, Box-2)

Horizontal fit among HR practices and processes.
The third variant of the horizontal fit within HPWS explains the inter-relationships of HR practices (within respective HR policy) and HR processes (within respective HR practice) and potential impacts of these inter-relationships on departmental and individual level performances respectively. The explanation of this inter-relationship is primarily based upon the comprehension of the 'overlapping effects' phenomenon, which states, 'the outcome can be achieved by applying either practice alone, and no additional benefit can be acquired by addition of more practices' (Chadwick,). This phenomenon helps draw the conceptual segregation between substitutive and additive relationships within a single HR policy/practice. As discussed above, every HR policy can use various implementable practices to acquire the desired outcome. Using the same logic, each HR practice can also use various HR processes to accomplish the common objective.
Moreover, each HR policy/practice can have multiple goals to achieve. Such as, to entice potential applicants, the recruitment policy can have two objectives: (1) how to enhance the organization's profile and (2) how to launch a suitable and well-organized channel to engage the potential job seekers. In this scenario, the achievement of these two sub-objectives could be accumulated to form a common objective. Now, to accomplish those two distinct sub-objectives, certain HR practices are needed. As the sub-objectives are usually different, the inter-relationships of those HR practices must be independent and non-overlapping to accomplish the respective sub-objectives simultaneously. In this scenario, the inter-relationships among HR practices are expected to be additive. The same logic can be applied to determine the nature of inter-relationship among different HR processes to acquire multiple sub-objectives of a particular practice. On the other side, if the objective or sub-objective of a specific HR policy/practice is not separable, the practices/policies related to those lower-level objectives would plausibly be substitutable and using distinct practices could yield the same results. In such situations, the execution of multiple practices/processes pursuing similar sub-objectives or policy/practice outcomes might overlap. It would not achieve any more significant impact as compared to executing them in isolation with each other. Theoretically, the underlying justification for substitutive relationships leads to the concept of equifinality, which states that two or more HR practices could be equally effective to acquire an organization's performance objectives. For instance, applying multiple practices like quality circles, off-line problemsolving teams, and other formal participation in decision-making practices is improbable to enhance participation and empowerment further than using one or two of them.
To conclude, when HR practices pursue distinct sub-objectives, the inter-relationships among HR practices are likely to be addictive. Once HR practices pursue similar subobjectives, the relationship among HR practices might be substitutive. The same is the case for HR processes within a particular HR practice. Therefore, the two discussed scenarios related to HR practices and HR processes are likely to influence performance at departmental and individual levels respectively (see Figure 1 Box-3 and 4), which is further linked with organizational level performance.

Vertical-fit within each HR domain
Within a HPWS, vertical fit describes the 'degree of fit' within an individual HR domain. It also refers to the alignment within the HR domain across macro and micro levels (e.g. HR policies, practices, and processes). A positive synergistic effect is produced through the interaction of an effective HR policy with an aligned HR practice, and the result is something superior and more affirmative than by just adding up the effects of two HR activities (1 + 1 > 2). Conversely, if that particular policy is instigated through a misaligned HR practice, it may generate a negative synergistic effect (1 + 1 < 2). Such type negative synergistic effects could yield more dysfunctional organizational results than from a singular HR activity. Therefore, the effectiveness of any HR policy is likely reliant upon or is moderated by the extent to which HR practices support it. Likewise, the effectiveness of any HR practice should be dependent on HR processes. Alignment/ misalignment within an HR domain across its macro and micro levels will generate positive /negative synergistic effects and eventually influence the performance at individual, departmental, and organizational levels. Let us consider an example to understand the concept of vertical fit within each HR domain; top management decides to apply a merit pay policy to impact employee motivation and job performance. To execute this, it utilizes a merit pay practice. The employees generally perceive that they get merit raises that show their inputs relative to colleagues; in that case, employees would feel the fair treatment. They would be motivated to deliver (Osterman, 1994). Resultantly, work effort and job performance should see a significant improvement. Conversely, suppose top management utilizes the same practice but based on their inputs. In that case, if employees feel that they remained under-rewarded compared to co-workers, their level of motivation and performance is likely to be negatively affected. Moreover, as employees anticipated to be rewarded based on their inputs (i.e. a merit practice exists) but their anticipations were not met (i.e. the corresponding merit pay process is absent), it can have a significant negative impact on work motivation and job performance (Posthuma et al., 2013;Rehmani et al., 2021).

Discussion and implications
The prime resolve of this research study was to explore the nature and types of internal relationships among HR elements within the construct of HPWS and to elucidate a theoretical rationale for internal-fit explaining how numerous components of HPWS operate together to affect performance at individual, departmental and organizational level. Based on the AMO framework (Han et al., 2020;Subramony, 2009;Z. Zhang & Jia, 2010) and prevailing insights of the types of effects and internal relationships within different HR systems (Chadwick,), it is anticipated that different types of inter-relationships (additive, substitutable, positive synergistic and negative synergistic) are expected to arise at distinct levels of HPWS based on the levels of abstraction and nature of respective objectives/sub-objectives. We expect that the current proposed framework will be helpful for a better appreciation of the HPWS construct (theoretical implications) and facilitate the researchers in correct operationalizing of HPWS construct while conducting measurement studies (methodological implications) in future research.
There are two critical dimensions involved and needs to be understood regarding HPWS construct. The external dimension is linked with the organizational output, and the desired business results as strategic HRM literature indicates that the fundamental cause of applying HPWS methodology is the strategic objective of an organization to achieve a significant improvement in its operational and financial outcomes. However, these outcomes cannot be practically materialized without having a proper comprehension of the inner fabric of the HPWS construct, and that is the point where the importance of exploring the internal dimension of the HPWS construct comes into play.
Organizational performance is the congruent and composite outcome of departmental performance, which relies on individual-level results. It is therefore essential to establish a horizontal and vertical fit among HR components at multiple levels. At the macro level, the synergy and congruence among three HR domains (horizontal fit) are necessary to influence organizational performance, as their effects are interdependent.
From a conceptual standpoint, a potential implication of this framework implies that while we incline to emphasis on system level thinking, policies from distinct HR domains may have significant impacts on multiple levels of performance. If this notion is true, it means that while the predominant HR system may be linked to individual, departmental and organizational performance, the relative influence of the three domains on performance may differ across the three distinct levels of performance. This implies that we could find a statistically significant association between organizational compensation policy and employee's motivation and commitment but not with employee's KSAs, likewise, between selection policy and employee's KSAs but not with employee's opportunities to contribute. It is also worth noting that, while we conceptualize specific HR policies within each domain, a single HR policy may be associated with multiple HR policy domains (Peccei & Voorde, ;Rehmani et al., 2020b). For instance, although training is rationally linked to employees' KSAs, it can also serve as a source of incentive for employees, particularly when used as a reward (Jyoti et al., 2015). Likewise, empowerment is likely to be linked with employee's opportunities to contribute but it can provide employees with motivation to perform as well (Peccei & Voorde,). Although the conceptual framework of the proposed model proposes that HR policies are aligned most significantly with a single HR policy domain, yet the possibility of potential relationships between HR practices from within, as well as between, HR policy domains and individual/departmental performance and ultimately, organizational performance cannot be overruled. The three distinct HR domains mutually explain the essence of HPWS. Each of these HR domains encompasses a distinct feature of the notion of HPWS, which is not covered by the others (e.g. enhancing KSAs, augmenting motivation, or creating opportunities). Their influence on HPWS is not substitutable, so, none of them can be used to represent and reflect HPWS in isolation. There are different antecedents for each domain and the variations in each domain may result in the change of the entire HPWS. In this scenario, instead of representing it as a common latent construct, all three HR domains jointly relate to an effective HR scheme. Therefore, inclusion of all three HR domains for a valid measure of HPWS is imperative irrespective of what particular policies, practices and processes are implemented within these domains. It will be an inappropriate approach to measure HR policies, practices and processes using only one or two domains of HPWS to draw the logical conclusions regarding the inter-relationships of the entire HPWS with other constructs. Any misalignment (horizontal or vertical) may contribute to feelings of inequity, unhealthy attitudes, and incongruent attempts by workers to achieve organizational objectives and increase the organization's effectiveness. Likewise, at the micro-level, within each HR domain, apart from the horizontal fit 'within' policies, practices and processes, a vertical fit 'among' policies, practices and processes is also imperative. The proposed framework helps to understand the nature and importance of this bi-dimensional fit and its potential link with a performance at multiple levels.

Limitations
We have proposed particular HR policies within each HR domain; however, it is more likely that a specific HR policy might be linked with more than one HR domain. For instance, training is rationally linked with KSAs domain; however, providing training as a reward might also motivate employees. Likewise, empowerment is anticipated to be related to employee's opportunities to contribute, but it can also motivate employees to perform well. Therefore, further research is required to investigate the relationships between HR practices and HR processes among different HR domains.

Directions for future research
We shall encourage future researchers to investigate the potential effects of contextual factors like the type of industry, organizational size, organizational structure, organizational culture and organizational climate etc., on the proposed internal relationships of this framework. It is also recommended to take into account various factors linked with the shifts due to the emergence of pandemic coronavirus (Covid-19) that either directly or indirectly will have an impact on the level of employee productivity and organizational performance.

Conclusion
In the proposed framework, the most relevant HR components of HPWS are identified and categorized in their respective levels of abstraction (macro and micro levels). The study explores the types and nature of inter-relationships among various HR components and delineates how these elements work together to influence performance at multiple levels. Lastly, the bi-dimensional 'internal-fit' concept of HR elements is applied to explain how positive and negative synergistic effects can arise within a coherent and internally aligned HPWS.