Account for the differences in perceived pressure to compromise personal standards of conduct among senior managers, middle managers, and lower managers. Are the actual pressures really different, or is there a difference in perception, or is there some other reason?

I doubt that there is any less pressure at higher levels of management than at lower levels. Thus, there must be other reasons for the difference in perception. One possible explanation is that the managers who have advanced to higher levels of management have become accustomed to the pressure, and so do not notice it as readily. Second, lower level managers have more direction provided to them (contrasted with upper level managers, many of whom set their own agendas and are more self-directed), which often comes across as pressure to achieve the desired objective, regardless of how it is done.