**2. Literature review**

In the 1940s, leadership was studied on the basis of the personal traits possessed by a leader such as physique, intelligence, cognitive ability, appearance, fluency of speech, knowledge, ambition, personal adjustment and emotional control. However, Bryman [22] argued that these traits solely cannot be recognised as factors of effective leadership, instead factors like situation, environment settings and the relationship with followers' matters in the role of effective leadership. Daft and Pirola-Merlo [1] have shown that a leader must have a variety of characteristics, namely personal characteristics, social characteristics and work-related characteristics. Personal characteristics deal with energy, physical stamina, intelligence, knowledge, judgement and decisiveness. Whereas, sociability, high interpersonal skills, cooperativeness and diplomacy are related to social characteristics. Work-related characteristics include stableness in the face of hurdles, accountability in pursuing goals and mobility. A recent research conducted by Eid et al. [3] proposed that leadership must have two traits: basic traits and motivational traits. Basic traits cover emotional stability, dominance, enthusiasm, conscientiousness, social boldness, tough-mindedness, self-assurance and compulsiveness. On the other hand, leaders must possess traits which help them motivate their followers. These traits include high energy, intuitiveness, maturity, team orientation, empathy and charisma. Over the years, various leadership styles were proposed based on some combination of these characteristics and traits. In last few decades, the influence of these leadership styles on employees was thoroughly investigated. The success of every business is governed by its employees urge to succeed through their efforts, commitment, engagement and practice. Therefore, it is the prime responsibility of leaders to motivate their subordinates with appropriate leadership styles and keep their aspirations high and achievable [23].

the input attributes and no information of output attribute is present. The task of any clustering algorithm is to find natural groupings in the data, where each group must have maximum similarity among grouped data instances and maximum dissimilarity across different group instances [18]. Customer segmentation, anomaly detection and identifying association rules

At organisational level, identifying and managing the needs of various stakeholders are core to the success of organisations. The stakeholder can be divided into internal and external stakeholders. Customers, government and local council are few examples of external stakeholders. Employees and management are the examples of the internal stakeholders of an organisation. A significant research has been carried out to improve the relationship between organisation and external stakeholders using data mining algorithms. However, there is inadequate research on applying data mining techniques to improve the relationship between different facets of the organisation. Extensive research has taken place in the literature that establishes the importance of relationship between employees and organisational management and how this relationship is core to the success of an organisation [19, 20]. The researchers have used statistical analysis techniques such as correlation and regression analysis to establish and understand this relationship [1, 4, 21]. However, no efforts are made to extract useful information from such databases. The main objective of this paper is to use data mining algorithms to extract actionable and interesting patterns in the database (the impact of

In the 1940s, leadership was studied on the basis of the personal traits possessed by a leader such as physique, intelligence, cognitive ability, appearance, fluency of speech, knowledge, ambition, personal adjustment and emotional control. However, Bryman [22] argued that these traits solely cannot be recognised as factors of effective leadership, instead factors like situation, environment settings and the relationship with followers' matters in the role of effective leadership. Daft and Pirola-Merlo [1] have shown that a leader must have a variety of characteristics, namely personal characteristics, social characteristics and work-related characteristics. Personal characteristics deal with energy, physical stamina, intelligence, knowledge, judgement and decisiveness. Whereas, sociability, high interpersonal skills, cooperativeness and diplomacy are related to social characteristics. Work-related characteristics include stableness in the face of hurdles, accountability in pursuing goals and mobility. A recent research conducted by Eid et al. [3] proposed that leadership must have two traits: basic traits and motivational traits. Basic traits cover emotional stability, dominance, enthusiasm, conscientiousness, social boldness, tough-mindedness, self-assurance and compulsiveness. On the other hand, leaders must possess traits which help them motivate their followers. These traits include high energy, intuitiveness, maturity, team orientation, empathy and charisma. Over the years, various leadership styles were proposed based on some combination of these characteristics and traits. In last few decades, the influence of these leadership styles on employees was thoroughly investigated. The success of every business is governed by its employees urge

in buying patterns of customers are few examples of clustering algorithms [14].

supervisors' leadership style on employees).

**2. Literature review**

142 Leadership

The effects of leadership styles (transformational and transactional) on different factors such as job performance, employee satisfaction and organisational commitment were studied indepth by Norwawi [24]. The author revealed that leadership styles were vital to organisational development. The author also concluded that by using appropriate leadership style, job satisfaction, stress, employee turnover and productivity could be controlled effectively. Caillier [25] has found in his study that transformational leadership affects the performance of the employee with high mission valence. The clarity in goals resulted in higher levels of motivation in employees. Wang et al. [26] found in their study that transformational leadership has a positive effect on organisational justice and job characteristics. It is found that employees outperform the targets if leaders with transformational leadership can set the goal with clear communication and can motivate them [27]. Employees find self-respect and put additional efforts to achieve the goals if they are challenged and if the goals are set at high levels [28].

Similarly, transactional leaders have clear expectations that are communicated to their employees regarding goal attainment and the rewards upon fulfilment of their contractual responsibilities [27]. Attainment of the time bound task in an organisation depends upon the clarity of the goal and expectations conveyed to its employees, which helps them perform better. The use of contingent rewards inspires the employees explicitly or implicitly to exert extra effort for goal attainment. On the contrary, management-by-exception passive has a negative association with employees generating extra effort and also laissez faire leadership style relates negatively to job commitments. At certain times, a combination of transactional and transformational leadership is used by the leaders to increase motivation and productivity. This hybrid leadership style is becoming very popular in organisations [27].

Alloubani et al. [4] conducted a study in healthcare sector in Jordan and investigated the relationship between leadership styles (laissez faire, transactional and transformational) and employees' motivation, satisfaction and effectiveness. They evidenced that transformational and laissez faire leadership styles significantly affect employee outcomes (motivation to work hard, satisfaction and effectiveness); transformational style affects positively and laissez faire affects negatively all of the employee outcomes.

Leadership style also has impacts on organisational commitment and employee job performance [29]. They found an appropriate leadership style that enhances employees' problemsolving skills and helps employees to innovate. But, it is important to devise a right leadership style to match followers' characteristics [23]. They found that situational leadership style is more effective where leadership styles are tailored according to the situation and the followers' characteristics. Situational leadership exhibits multiple leadership styles and is more prevalent in contemporary organisations, encourages workforce diversity and brings optimal outcomes. The finding on the relationship between leadership styles and employee outcomes in existing literature is inconclusive in nature. This is one of the main reasons why data mining is most appropriate method to extract the trends and pattern out of this complex relationship between leadership styles and employees' outcomes.
