AGE OF COW AND BUTTER-FAT PERCENTAGE 91 



As noted elsewhere the linear equations are not suited to the 

 description of the relation between milk yield and age. The data 

 are given merely for sake of illustration. It is realized that the 

 description of the method is given in the most elementary terms. 

 The student will find the reading of G. U. Yule, An introduction 

 to the theory of statistics, J. B. Lippincott Company, Philadelphia, 

 Chapters VI to X, of value. 



In the student's paper on the relation between age and butter-fat 

 percentage in cattle, it would be desirable to take one of the numerous 

 tables for these relations to be found in the references and check over 

 the calculations and form the curves. The student would do well 

 to consider and discuss the question of whether or not the effect of 

 age on butter-fat percentage is the same in all breeds of cattle. 



REFERENCES 

 See those of Chapter XI. 



