In the field of corporate diagnosis is a process that involves the three steps of publicly entering a human system, collecting valid data about experiences, and feeding back to the system toward promoting corporate performance.
The effective diagnosis of organizational culture, and structural and operational strengths and weaknesses are fundamental to any successful organizational development intervention. As Beckhard said in the preface to his seminal work:
In our rapidly changing environment, new organization forms must be developed; more effective goal-setting and planning processes must be learned, and practiced teams of independent people must spend real time improving their methods of working, decision-making and communicating. Competing or conflicting groups must move towards a collaborative way of work. In order for these changes to occur and be maintained, a planned, managed change effort is necessary - a program of organizational development.
This was written in 1969 and while much has been learnt it is just as true today.
Since the beginnings of organizational development as a profession, diagnosis has moved from the purely behavioral towards a strategic and holistic business diagnostic approach, and from looking at human interventions in isolation to exploring the interactions of people in the context in which they operate. As organizations are more collaborative in nature, the traditional silo approach to diagnostics is becoming increasingly rare. Organizational development and in particular the diagnostic phase of activities is spreading from the occupational psychologists towards mainstream business. This is important for OD practitioners as the role is increasingly holistic.