INDUSTRIA L MA THEM. I JIC\'^ 291 



unusually bad. By the use of suitable routines set up in accordance with 

 statistical theory, the day-to-day results of inspection can be used to detect 

 incipient degradation in the process of manufacture which might otherwise 

 escape notice. This procedure is used extensively by the Western Electric 

 Company in assuring uniform quality in many items of manufacture, and 

 to a lesser extent in other industries. Of it, Mr. J. M. Juran, Manufactur- 

 ing Engineer of the Western Electric Company, says: 



"Too frequently we have seen an inspection group grow lax hi vigilance until a 

 complaint from the customer wakes them up. They promptly swing the pen- 

 dulum a full stroke in the opposite direction, and the factory groans in its effort 

 to meet the now unreasonable demands. A sound and steady control, like a 

 sound currency in commercial relations, gives factory foremen a feeling of confi- 

 dence and gives the consumer a feeling that control is being exercised before the 

 product reaches him."^" 



(e) In writing rational specifications. Obviously, if such a procedure 

 helps the manufacturer to assure uniform quality, it is also of value to the 

 purchaser of his products. Hence the subject of statistics enters into 

 the writing of the buyer's specifications. It has been so used to a limited 

 extent in the Bell System in connection with telephone apparatus, and by 

 the United States Government in the purchase of munitions. However, 

 it must still be rated as a relatively undeveloped field. Of it, Captain 

 Leslie E. Simon, Ordnance Department of the United States Army, says: 



"Statistical methods have proved to be a powerful tool in the critical examina- 

 tion of some ammunition specifications prior to final approval. Their use, either 

 directly or indirectly, is almost essential in determining a reasonable and economic 

 standard of quality through the method of comparing the quality desired with 

 that which can be reasonably expected under good manufacturing practice. In 

 like manner, the statistical technique renders a valuable service in framing the 

 acceptance specification. Through its use the quantity and kind of evidence 

 which will be accepted as proof that the product will meet the standard of quality 

 can be clearly expressed in a fair, unequivocal and operationally verifiable way." 



Conclusion 



It is perhaps unusual to conclude a survey of this sort by stating the 

 impressions which it has made upon its writer. In the present instance, 

 however, the element of self-education has been so large that these im- 

 pressions may summarize the report better than any more formal recapitu- 

 lation. They are: 



^^ "Inspectors' Errors in Quality Control," by J. M. Juran, Mechanical Engineering, 

 Oct., 1935, pp. 643-644. 



