VARIABILITY OF A SINGLE CHARACTER 1 1 5 



feet, or what not — and the "class marks" 1 fixed, then the 

 student is ready for measurements. The next question is where 

 to record the various individuals measured. For example, sup- 

 pose in measuring corn we have adopted the scheme, 4.0, 4.5, 

 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, etc. We will rarely find an ear that 

 measures exactly on the even inch or half inch. Most of them 

 will fall somewhere between these various marks and will need 

 to be assigned to one group or another somewhat arbitrarily. 

 Now the rule is to assign to the nearest group. Thus suppose 

 an ear measures j\ inches; it would be put into the 7.0-inch 

 class because it is nearer 7 inches than it is to any other measure- 

 ment of our scheme. Should it measure 6] inches, it would 

 also go into the 7.0-inch class, and in doing so it would correct 

 the slight error made in putting the other ear into a class too 

 short for it. On the principle that as many will be too long as 

 will be too short, we depend upon the law of chance 2 to keep 

 our errors even. 



On the same principle, if the ear should read 7|, it would go 

 into the 7. 5 -inch class ; but if it should be 7 J, it would stand 

 exactly halfway between the two classes, and here a careful de- 

 cision must be made as to where it should be put. As it stands 

 midway between 7 and 7.5 there are no more reasons for its 

 going one way than the other, and in choosing a scheme of 

 measurements it is well to avoid a scale that is likely to make 

 too many fall upon this middle point. 



There are but two things to be done with these midclass 

 measures. They can all be put into the class above them, on 

 the principle of the business man that calls half a cent a whole 

 cent and then discards all smaller fractions ; or, what is more 

 accurate, every alternate measurement of this kind may be put 

 once above and next below; that is, the first time a 7.25 

 measurement occurs it may be called 7.5, and then, to offset the 



1 The class marks are the various measurements, as 4 inches, 4.5 inches, 

 5 inches, etc., that make up the scheme of measurements. 



2 " Principles of Breeding," p. 365. 



