The Use of Lognormal Distribution to Portray Quality Improvement Trends

Introduction: AT&T Bell Laboratories has embarked on a significant quality initiative in 1987. The goal of this initiative is to improve the quality of software and hardware/device products by a factor of ten in five years, and to document quality plans for all projects. To support this initiative and to track the progress we made, summary information on quality levels and trends were issued quarterly in the AT&T Bell Laboratories Quality Metrics Report (BLQMR). In this paper, we shall study the probable improvement trajectory for a group of projects, and identify the assumptions of a model, which would allow us to address the above concerns.