EXACT METHODS IN SOCIOLOGY. 157 



ent phenomena under examination in the same treatise. There 

 is no uniformity of measurement. !Now, it is easy to introduce 

 uniformity, even where arithmetical values are not kno\vn. It is 

 possible to know that we are applying the same method of meas- 

 urement when we say that, since 1850, there has been a " great " 

 multiplication of lynchings in the United States that we apply when 

 we say that there has been a " great " increase of population, al- 

 though, in the case of the lynchings, we have not arithmetical 

 values, while in the case of the increase of population we have. 



This can be done in the following way: Distinguish and des- 

 ignate degrees of increase or decrease by symbols thus: Ko change, 

 = 0; absolute increase but relative decrease, = + 1; absolute in- 

 crease with no relative decrease, = + 2 ; great absolute increase 

 without relative decrease, = + 3; absolute and relative increase, 

 = + 4; absolute decrease but relative increase, =^—1; absolute 

 decrease without relative increase, = — 2 ; great absolute decrease 

 without relative increase, = — 3; absolute and relative decrease, 

 = -4. 



ISTow let the historian who wishes to pass in review the quanti- 

 tative changes that have occurred since a given time — for exam- 

 ple, 1850 — before he puts on paper his impressions, based upon 

 such evidence as he has been able to collate, put down all these 

 s;yTnbols against the name of each of the social phenomena which 

 he is studying. He will instantly see that he is trying to apply 

 to each of the phenomena whose changes he wishes to record a 

 certain scale of measurement, and he at once asks himself: What 

 do I really mean by such a term as " relative " increase or decrease 

 when contrasted with " absolute " increase or decrease; and what 

 do I mean by such a term as " great " increase or decrease when 

 contrasted with such a term as " increase " or " decrease " without 

 a modifying word? The moment he puts these questions before 

 his mind he will feel a sinking of heart as he reviews the pages 

 in which he has confidently told his readers that such " absolute " 

 and " relative " changes have from time to time occurred, and re- 

 flects that he has seldom been consistent in his use of these terms. 



How, then, shall he attain consistency and precision? To be 

 consistent and precise in the use of the word " relative " it is 

 necessary to make at the outset an arbitrary choice of a term of 

 comparison, just as in making comparative judgments of such a 

 phenomenon as general intelligence it is necessary to take as a 

 standard the phenomenon as observed in a particular community. 

 The most suitable term of comparison for all judgments of increase 

 or decrease in social phenomena is the increase or decrease of popu- 

 lation per square mile within the 'area and during the period stud- 



