THE L3 SYSTEM — QUALITY CONTROL REQUIREMENTS 967 



action on the process. Close to 100 per cent packaging can be assured by 

 introducing a negative bias in the process to compensate for the effect 

 of a prior positive bias, and vice versa. 



5.0 Conclusions 



The L3 system's need for holding transmission performance close to 

 the design center, both Avithin short segments and over the full span of 

 the transcontinental line, has called for a high degree of statistical uni- 

 formity of critical characteristics of component elements. The statistical 

 quahty control methods are imposed from the point of view of the user 

 in the interests of the over-all economy of system design. The control 

 procedures are designed to provide at all times a parade of suitably dis- 

 tributed batches of production units, and at the same time to furnish 

 incentives for controlHng manufacturing processes at the design center. 



Any enterprise of this kind, involves the closest of interplay and ad- 

 justment between design and production interests. Many cases of in- 

 compatibility of design desires and production capabilities had to be 

 cleared in the early stages of the work. Intensive process quality con- 

 trol work and the development of a number of ingenious processing 

 techniques on the part of the Western Electric Company have con- 

 tributed greatly to what has been achieved. Experience will undoubtedly 

 indicate the need for some refinements or adjustments in the plan. 



Acknowledgments 



The authors wish to express their appreciation to members of the 

 Western Electric Company's engineering organization for cooperation 

 in the development of the general plan, to Miss M. N. Torrey and Dr. 

 R. B. Murphy for development work on statistical features of alternate 

 and final plans, and to the Misses E. F. Lockey and J. Zagrodnick for 

 conducting sampling experiments and making computations. 



