“The term "principal" will denote a person who works in an office and whose productivity is, or could be, substantially enhanced by secretarial support. Princip

“The term "principal" will denote a person who works in an office and whose productivity is, or could be, substantially enhanced by secretarial support. Principals' roles include manager, administrator, and professional; and they are found in all major industries, in government, and in education, law, and medicine. [...] The productivity of many principals is difficult to measure. We shall not deal explicitly with this problem.” Someone whose output is hard to directly measure? How does this differ from other indirect job roles?