A METHOD OF GRAPHICAL ANALYSIS 



87 



ordinates of the plane surface. Message use is indicated by the 

 rings on the upright pegs. 



In general, the various steps in the analysis leading up to the final 5 

 or normal 6 relationships require continuous exercise of judgment. 

 The problem is never one of securing simply curves of "best fit" to 

 the data. It is broader, more fundamental and much more involved 



Fig. 3C 



than this. It requires a combination of logic with the data that results 

 in normal relationships which fit the data and at the same time are 

 reasonable. It is necessary to consider such questions as the follow- 

 ing: Why do the data indicate this relationship? As a generalization, 

 is such a relationship reasonable? What should be the character of 

 this relationship? Should it be a straight line, concave up or con- 

 cave down? Particular attention is given to the reasonableness of 

 maxima or minima points and to points of inflexion when indicated 

 by the data. It is only by considering such fundamental questions 

 that a sound basis can be established for building up normal rela- 



6 Final in a relative sense. In economic studies of this type involving human 

 reactions and relationships normal relationships are never final in an absolute sense. 



6 The term "normal curve" is used throughout this paper to designate a final 

 curve from which estimates are to be made. A normal distribution curve in this 

 sense may or may not be "normal" in the statistical sense of an evenly balanced 

 bell-shaped curve. 



