88 BELL' SYSTEM TECHNICAL JOURNAL 



tionships which will be a true generalization of experience. The 

 importance of dealing with economic problems in this way can hardly 

 be over emphasized. It is a recognition of the complexities which 

 are inherent in problems involving human reactions and the dangers 

 of untrue generalization if rigorous and more or less inflexible methods 

 of analysis are utilized. 



Final Results 



The result of the smoothing process is the development of a con- 

 sistent series of charts and curves by means of which the value of the 

 dependent variable may be estimated from the values of the various 

 independent variables. 



AVERAGE RANK OF SERVICE 



Fig. 4 — Final Family of Curves 



Fig. 4 is an example of such a chart for estimating average 

 message use. Charts of this type may be used under proper 

 conditions for estimating either an actual value which is unknown 

 (such as average message use under an existing rate schedule) or 

 the value which may be expected to result from some change 

 (such as average message use under a proposed rate schedule). 



