How do the Employees’s Perceptions of Abusive Supervision A ﬀ ect Customer Satisfaction in the Chain Restaurants? Employee-Customer Level Analysis

: The purpose of this study is to examine the e ﬀ ect of chain restaurant employees’ perception of abusive supervision on employee satisfaction and customer satisfaction. The sample for the survey was collected from 228 customers and 93 employees in a chain restaurant. The results showed a negative relationship between abusive supervision and employee satisfaction. However, abusive supervision did not have a signiﬁcant, direct e ﬀ ect on customer satisfaction, but showed an indirect e ﬀ ect via employee satisfaction. In addition, employee satisfaction was positively associated with customer satisfaction.


Introduction
In recent years, destructive leadership and related issues have received growing attention, with research undertaken on the effects of abusive supervision, in particular. Research findings have suggested that a supervisor's abusive behavior in the workplace leads to employees' negative performance and incurs organizational costs [1,2]. Such behavior can be seen as abusive leadership, which Schyns and Schilling [3] defined as how the activities, experiences, and relationships of individuals or group members are repeatedly affected by a supervisor over a long period of time. The term abusive supervision [4] is most frequently referred to in relation to destructive leadership. Tepper [5] defined it as long-term abuse of subordinates through actions that include mockery, threats, intentional holding back of information, or silence. Many studies have cited abusive supervision as a principal cause of employees' chronic disability or stress [6][7][8]. Until now, researchers have paid most attention to positive leadership, focusing on a supervisor's dynamic roles in enhancing employees' work satisfaction [9,10]. The effect of bad leadership remains largely unknown. We therefore aimed to illuminate the dark side of leadership that negatively affects employee satisfaction and customer satisfaction. This study starts from the question of whether an abusive supervisor can make not only employees but also customers leave. There are many studies on work satisfaction and customer satisfaction, and yet little is known about the role of an abusive supervisor in triggering dissatisfaction.
Particularly in the foodservice industry, employees' attitudes and consequent service quality play a key role in creating a pleasant experience for customers and increasing their satisfaction; thus, internal marketing is of utmost importance to improve customer satisfaction [11,12]. Further, foodservice customers tend to be loyal to several restaurants at a time, and thus it is very important for restaurants to make good use of their human resources to ensure customer satisfaction and set their restaurants apart from others [13]. Many studies have been conducted to date on the effect of abusive supervision on employees' psychological well-being and work attitude [14][15][16]. No studies have been conducted on the Information 2020, 11, 384 2 of 10 effect of abusive supervision on customer satisfaction through the mediation of employee satisfaction because paired data between employees and customers are hard to collect, complicated, and costly. However, such a survey was conducted for this study, with the aim of assessing various suggestions made to date in the foodservice industry that have yet to be fully explored. We analyzed a path model that emphasized correlation between abusive supervision, employee satisfaction, and customer satisfaction, to test hypotheses that abusive supervision negatively affects employee satisfaction, which in turn reduces customer satisfaction ( Figure 1).
Information 2020, 11, x FOR PEER REVIEW 2 of 10 for restaurants to make good use of their human resources to ensure customer satisfaction and set their restaurants apart from others [13]. Many studies have been conducted to date on the effect of abusive supervision on employees' psychological well-being and work attitude [14][15][16]. No studies have been conducted on the effect of abusive supervision on customer satisfaction through the mediation of employee satisfaction because paired data between employees and customers are hard to collect, complicated, and costly. However, such a survey was conducted for this study, with the aim of assessing various suggestions made to date in the foodservice industry that have yet to be fully explored. We analyzed a path model that emphasized correlation between abusive supervision, employee satisfaction, and customer satisfaction, to test hypotheses that abusive supervision negatively affects employee satisfaction, which in turn reduces customer satisfaction ( Figure 1).

Relationship between Abusive Supervision and Employee Satisfaction
Tepper [5] explained that abusive supervision is a subordinate employee's perception of the supervisor in relation to the extent of the display of hostile verbal and nonverbal behaviors that do not include physical contact. Most studies on abusive supervisors have shown that an abusive supervisor's behaviors-expressed in the form of destructive leadership-did not result in constructive employee behavior [17,18]. Work satisfaction is a principal topic of research in the workplace [19]; it indicates development of favorable emotion toward one's work, based on evaluation of work experience [20]. The more abusive the supervisor, the weaker the acknowledgment of distributive justice and the lower the level of work satisfaction [21]. Similarly, Lin, Wang and Chen [22] argued that an abusive supervisor hurts the employees' well-being, especially through poorer mental health and lower work satisfaction. Ahmad, Khattak, and Ahmad [23] also asserted that employees experience unwanted emotions and responses due to an abusive supervisor's behaviors, and thus grow dissatisfied with work. Kernan et al. [24] maintained that a supervisor's abusive behaviors make their subordinates feel insulted, thereby negatively affecting their work satisfaction. Mathieu and Babiak [25] argued that swearing and other nonverbal abusive behaviors displayed to subordinates have an absolute influence on reducing work satisfaction, while Qian, Song, and Wang [26] found that a supervisor's insulting words and behaviors are closely tied to their subordinates' work dissatisfaction. Peltokorpi and Ramaswami [27] observed that abusive supervision affects subordinates' work satisfaction negatively, caused by the employees' negative response to why they are mistreated. In summary, higher abusive supervision leads to lower job

Relationship between Abusive Supervision and Employee Satisfaction
Tepper [5] explained that abusive supervision is a subordinate employee's perception of the supervisor in relation to the extent of the display of hostile verbal and nonverbal behaviors that do not include physical contact. Most studies on abusive supervisors have shown that an abusive supervisor's behaviors-expressed in the form of destructive leadership-did not result in constructive employee behavior [17,18]. Work satisfaction is a principal topic of research in the workplace [19]; it indicates development of favorable emotion toward one's work, based on evaluation of work experience [20]. The more abusive the supervisor, the weaker the acknowledgment of distributive justice and the lower the level of work satisfaction [21]. Similarly, Lin, Wang and Chen [22] argued that an abusive supervisor hurts the employees' well-being, especially through poorer mental health and lower work satisfaction. Ahmad, Khattak, and Ahmad [23] also asserted that employees experience unwanted emotions and responses due to an abusive supervisor's behaviors, and thus grow dissatisfied with work. Kernan et al. [24] maintained that a supervisor's abusive behaviors make their subordinates feel insulted, thereby negatively affecting their work satisfaction. Mathieu and Babiak [25] argued that swearing and other nonverbal abusive behaviors displayed to subordinates have an absolute influence on reducing work satisfaction, while Qian, Song, and Wang [26] found that a supervisor's insulting words and behaviors are closely tied to their subordinates' work dissatisfaction. Peltokorpi and Ramaswami [27] observed that abusive supervision affects subordinates' work satisfaction negatively, caused by the employees' negative response to why they are mistreated. In summary, higher abusive supervision leads to lower job satisfaction, while lower abusive supervision leads to higher job satisfaction. Given these findings, the following hypothesis was proposed:

Hypothesis 1 (H1).
Abusive supervision is negatively related to employee satisfaction.

Relationship between Employee Satisfaction and Customer Satisfaction
Locke [28] defined employee satisfaction as a pleasant emotional state that can help to achieve work value for the employee or facilitate such achievement. Gundersen, Heide, and Olsson [29] defined customer satisfaction as postpurchase evaluation of the product or service. Many studies have shown a highly positive relationship between work satisfaction and customer satisfaction. Research has shown that satisfied employees can give greater satisfaction to customers [30,31]. Similarly, Spinelli and Canavos [32] found a tight correlation between employee satisfaction and customer satisfaction and that a customer reacts highly favorably to nimble and competent workers who are satisfied with their work. Moreover, employees who are satisfied with their work can elicit loyal customer behaviors [33]. Employee satisfaction is a core issue of interest in the service industry [34]. There is a very strong positive correlation between employee satisfaction and customer satisfaction. Customer satisfaction is particularly important in the service industry [11]: the more satisfied the employees, the easier it is to retain customers, leading to the greater financial performance of the company thanks to positive word of mouth from satisfied customers. Jeon and Choi [35] argued that employee satisfaction affects customer satisfaction positively, but not the other way around, and thus the two have a unidirectional relationship. Overall, the literature suggests that employee satisfaction is an important antecedent for improving customer satisfaction [36][37][38][39][40][41]. In view of the existing empirical evidence, the following hypothesis was formulated: Hypothesis 2 (H2). Employee satisfaction is positively related to customer satisfaction.
In consideration of hypotheses 1 and 2, it can be surmised that employees' perception of abusive supervision would possibly affect customer satisfaction through the mediation of employee satisfaction. Lyu, Zhou, Li, Wan, Zhang, and Qiu [42] argued that abusive supervision lowers employees' satisfaction, which in turn negatively affects employees' customer-oriented service behavior. Given this, it would certainly reduce customer satisfaction. Accordingly, the following hypothesis was proposed: Hypothesis 3 (H3). Employee satisfaction mediates the relationship between abusive supervision and customer satisfaction.

Samples and Procedures
We prepared two surveys to test these three hypotheses while reducing common method bias (CMB) error. One survey measured employees' perception of abusive supervision and their work satisfaction, and the other measured customer satisfaction. For the survey, we obtained consent from the managers of five family chain restaurants in Seoul, Republic of Korea-the top five of 2018-and handed out the survey to 10 servers at each restaurant. We assumed that three people, on average, sit at one table, and accordingly, for two stores of one family restaurant chain, we distributed 20 copies of the employee survey and 60 copies of the customer survey. For Time 1, employees replied with their perception of abusive supervision and their level of work satisfaction; for Time 2, customers reported their level of satisfaction with the same employees' service. The servers were asked to select customers who would participate in the survey. In cooperation with the restaurant managers, we conducted a survey for customers during their wait for dessert. To facilitate the process, complimentary drinks were provided to the customers, and we offered a small fee to the participating restaurants. Out of 100 employee surveys, 93 legitimate replies were returned (a 93.0% return rate). To measure customer satisfaction with the servers' service quality, the same server's customers were asked to take the survey, matching the two sets of surveys. Unmatched replies were omitted, and the final sample of customers totaled 228, an average of 2.45 customers for each server. Subsequently, we tested the hypotheses with the sample data from 93 employees and 228 customers.

Instrument Development
The study measures were grouped into four categories: demographic characteristics, abusive supervision, employee satisfaction, and customer satisfaction. The original survey questions in English were translated to Korean, according to Brislin [43], and Paramewaran and Yaprak [44].
Part one of the questionnaire contained the demographic characteristics of employees and customers (e.g., age, gender, and education). The survey instrument that measured abusive supervision, employee satisfaction, and customer satisfaction used a 7-point Likert scale: "How much do you agree or disagree with these statements?" (1: strongly disagree, to 7: strongly agree). To measure employees' perception of abusive supervision, the present study adopted 15 items from the scales created by Tepper [5] and Lyu et al. [42]. Sample items included: "My supervisor . . . expresses anger toward me when he/she is mad for another reason," " . . . puts me down in front of others," and " . . . is rude to me." To measure employees' satisfaction, this study adapted the scales of Spector [45], Netemeyer, Boles, McKee, and McMurrian [46], and Yang [47] and examined five items, which included: "In general I am satisfied with my job", "I like doing the things I do at work", and "I sometimes feel my job is meaningful." Customer satisfaction was measured by five items based on Bitner and Hubbert [48], Fornell, Johnson, Anderson, Cha, and Bryant [49], and Fishbein and Ajzen [50]. These items included: "I really enjoyed myself at the restaurant", "I am pleased to visit this restaurant", and "Overall, I am satisfied with my experience at this restaurant."

Data Analysis
Descriptive statistics and frequency analysis were performed to make a profile of the samples using SPSS 16.0. Following the two-step approach recommended by Anderson and Gerbing [51], a confirmatory factor analysis (CFA) with maximum likelihood was measured to estimate the measurement model. Finally, structural equation modeling (SEM), using AMOS 5.0 (the maximum likelihood method), was conducted to test the research hypotheses.

Sample Profile
The sample profiles are shown in Table 1. The employees' (N = 93) demographic characteristics were as follows. Half of the respondent employees (51.7%) were in the age group 30-39, and there were more females (74.2%) than males (25.8%). More than half (60.3%) had at least a university degree. Customers' (N = 228) demographic characteristics were as follows: 41.6% were 20 to 29 years of age, and slightly over half of the respondents (57.5%) were female. Most customers (68.4%) had a university degree.

Measurement Model
As shown in Table 2, the measurement model indicated a good fit (χ 2 = 995.87, df = 272, χ 2 /df = 3.66; goodness of fit index (GFI) = 0.80; normed fit index (NFI) = 0.88; comparative fit index (CFI) = 0.91; root square error of approximation (RMSEA) = 0.09). All standardized factor loadings exceeded 0.70, and each indicator's t-value exceeded 10.0 (p < 0.001) [51]. Composite reliabilities (0.92 to 0.96) and Cronbach's alpha (0.93 to 0.98) indicated internal consistency of the construct. In addition, the average variance extracted (AVE) value was greater than the squared values of the coefficients (Table 3). Average shared variance and maximum shared variance were smaller than the AVE value; thereby, the discriminant validity of the model was verified (Table 3) [52,53]. A review of the correlation between the measured items showed that employee satisfaction and customer satisfaction had a Information 2020, 11, 384 5 of 10 negative correlation with abusive supervision. The direction of the correlation therefore complied with the hypotheses.

Structural Equation Modeling
The structural equation model fit was good (χ 2 = 998.28; GFI = 0.74; NFI = 0.87; CFI = 0.91; RMSEA = 0.09). Table 4 presents the estimated model, illustrating the direction and magnitude of the impact of the standardized path coefficients. The employees' perception of abusive supervision negatively predicted employee satisfaction (β = −0.38; t = −6.12; p < 0.001), supporting Hypothesis 1. Employee satisfaction (β = 0.51; t-Value = 8.25; p < 0.001) had a significant effect on customer satisfaction; Hypothesis 2 was therefore supported.   Table 5 shows the mediating effect of employee satisfaction on how employees' perception of abusive supervision affected customer satisfaction (Hypothesis 3). Four conditions of Baron and Kenny [54]-a significant relationship among the independent, dependent, and mediating variables-were confirmed, as shown in Tables 3 and 4. According to the analysis, the direct impact of abusive supervision on customer satisfaction was not significant in the mediating model (β = −0.09; t = −1.55; p > 0.05), but it turned out significant in the restricted model (β = −0.27; t = −4.43; p < 0.001), as did the difference in χ 2 (∆χ2(∆df = 1) = 50.92; p < 0.05) between the restricted model (χ 2 (df = 273) = 1046.79) and the mediating model (χ 2 (df = 272) = 995.87). These findings confirm that employees' perceptions of abusive supervision negatively affect customer satisfaction through full mediation of employee satisfaction. Hypothesis 3 is therefore also accepted.

Discussion of Results
The objective of this study was to figure out the interrelationship of abusive supervision, employee satisfaction and customer satisfaction at chain restaurants. According to the analysis results, abusive supervision negatively affected employee satisfaction, supporting previous studies on abusive supervision and employee satisfaction [25,26] A positive causal relationship was observed between employee satisfaction and customer satisfaction [11,35], suggesting that abusive supervision reduces employee satisfaction, which in turn lowers customer satisfaction significantly. This study verified the secondhand influence of employee satisfaction, by showing that abusive supervision negatively affects customer satisfaction through the mediation of employee satisfaction. In other words, with abusive supervision, employees grow dissatisfied with their workplace and work, fail to provide satisfying service to customers, and thus negatively affect customer satisfaction.

Theoretical and Practical Implications
This study makes several theoretical and practical contributions. It provides useful data to understand the organic relationship between abusive supervision, employee satisfaction, and customer satisfaction. Previous studies mostly examined employees' psychological responses or attitudes toward perceived abusive supervision. However, this study set customer satisfaction as the final dependent variable and took an exploratory approach, with a focus on the relationship between abusive supervision, employee satisfaction, and customer satisfaction. As the first of its kind, this study is expected to provide useful information about related issues. We found that customer satisfaction is not directly reduced by abusive supervision, but rather through the mediatory role of employee satisfaction. Another academic contribution is that paired-surveys were conducted by matching chain restaurant servers and customers to minimize CMB error.
One of the practical contributions of this study is that it highlights that employees' work dissatisfaction can be quite costly at an organizational level, given the significant ripple effect of the negative influence of abusive supervision. When employees feel that they are abused by their supervisor, their work satisfaction falters, which eventually affects the service they provide to customers, resulting in reduced customer satisfaction. Since abusive supervision affects both employee satisfaction and customer satisfaction, all-out efforts are needed at an organizational level to deter abusive supervision. Specifically, it is necessary to manage a systematic supervisory program and encourage internal whistle-blowing to prevent abusive supervision, considering that employees who work with abusive and insulting supervisors tend to replicate such behaviors, even in worse forms [55]. It might also be advisable to conduct continued training and education at an organizational level, develop a program and provide coaching to improve supervisor−employee relationships, and support leisure activities. Supervisors need to learn management skills to properly treat and interact with employees, and these need to be continuously monitored to prevent abusive supervision. Additionally, leadership training needs to be conducted to foster ideal leadership for supervisors and enable efficient communication with employees. As a result, it was suggested that systematic management of abusive supervision at the organizational level is essential to improve organizational performance.

Limitations and Future Research
Despite these benefits, this study poses several limitations. First, the research sample consisted of chain restaurant servers and customers as a subcategory of the foodservice industry. Thus, the outcomes may be only applicable to a particular customer segment. There may also be variable errors due to the use of convenience sampling. In future research, comparative analysis needs to be conducted with an expanded sample from other companies within the foodservice industry. Second, it was observed that abusive supervision indirectly affected customer satisfaction through the mediation of employee satisfaction. More research needs to be undertaken to test a direct effect of abusive supervision on customer satisfaction.
Author Contributions: The authors contributed equally to this work. All the authors contributed to the conceptualization, formal analysis, investigation, methodology, writing of the original draft, and review and editing. All authors have read and agreed to the published version of the manuscript.