The Canadian academic, Henry Mintzberg who had trained as a mechanical engineer, wrote his PhD thesis at the MIT Sloan School of Management analysing the actual work habits and time management of chief executive officers (CEOs). In 1973, Mintzberg's thesis on the nature of managerial work was adopted as a study and published for a wider audience.

Mintzberg's empirical research involved observing and analysing the activities of the CEOs of five private and semi-public organisations. Previous management behaviour studies had concentrated on team and subordinate behaviour or organisational structure rather than on the day-to-day reality of managerial behaviour.

To describe the work life of a CEO, Mintzberg first identified six characteristics of the job:

1. Managers process large, open-ended workloads under tight time pressure - a manager's job is never done.
2. Managerial activities are relatively short in duration, varied and fragmented and often self-initiated.
3. CEOs prefer action and action driven activities and dislike mail and paperwork.
4. They prefer verbal communication through meetings and phone conversations.
5. They maintain relationships primarily with their subordinates and external parties and least with their superiors.
6. Their involvement in the execution of the work is limited although they initiate many of the decisions.

Mintzberg then identified ten separate roles in managerial work, each role defined as an organised collection of behaviours belonging to an identifiable function or position. He separated these roles into three subcategories: interpersonal contact (1, 2, 3), information processing (4, 5, 6) and decision making (7-10).

1. FIGUREHEAD: the manager performs ceremonial and symbolic duties as head of the organisation;
2. LEADER: fosters a proper work atmosphere and motivates and develops subordinates;
3. LIASION: develops and maintains a network of external contacts to gather information;
4. MONITOR: gathers internal and external information relevant to the organisation;
5. DISSEMINATOR: transmits factual and value based information to subordinates;
6. SPOKESPERSON: communicates to the outside world on performance and policies.
7. ENTREPRENEUR: designs and initiates change in the organisation;
8. DISTURBANCE HANDLER: deals with unexpected events and operational breakdowns;
9. RESOURCE ALLOCATOR: controls and authorises the use of organisational resources;
10. NEGOTIATOR: participates in negotiation activities with other organisations and individuals.

Mintzberg next analysed individual manager's use and mix of the ten roles according to the six work related characteristics. He identified four clusters of independent variables: external, function related, individual and situational. He concluded that eight role combinations were 'natural' configurations of the job:

1. contact manager -- figurehead and liaison
2. political manager -- spokesperson and negotiator
3. entrepreneur -- entrepreneur and negotiator
4. insider -- resource allocator
5. real-time manager -- disturbance handler
6. team manager -- leader
7. expert manager -- monitor and spokesperson
8. new manager -- liaison and monitor

Mintzberg's study on the 'nature of managerial work' exposed many managerial myths requiring change such as replacing the aura of reflective strategists carefully planning their firm's next move with one of fallible humans who are continuously interrupted. Indeed, half of the managerial activities studied lasted less than nine minutes. Mintzberg also found that although individual capabilities influence the implementation of a role, it is the organisation that determines the need for a particular role, addressing the common belief that it predominantly a manager's skill set that determines success. Effective managers develop protocols for action given their job description and personal preference, and match these with the situation at hand.