INTRODUCTION
The paucity of available evidence about actual changes occurring within the big firms, especially from the 1970s onward, poses a major difficulty in conducting this kind of research. Without statistical analysis, the court cases, regulatory investigations, and press reports of alleged audit failures can be dismissed by leaders of the profession as isolated instances, not representative of the general way in which the big firms fulfill their professional obligations. Of necessity, I relied on letters from those who do know, on public expressions of concern by leaders of the profession and by regulators, and on the writings by close students of the profession. I formed interpretations and conclusions based on the available evidence, and I welcome comments and reactions from readers