BY H. S. HALCRO VVARDLAW. 



851 



standard. The frequency curve also shows that, in the present 

 results, the most probable value of the percentage of solids not 

 fat is 8-65. This value is very close to the standard, which, 

 therefore, allows a very small margin of variation. Over 90% of 

 these results, on the other hand, lie above a percentage of solids 

 not fat of 7*9. 



In the preceding discussion, three forms of mean value have 

 been used, the arithmetic mean, the median, and the mode or 

 most probable value. In series of results which are symmetri- 

 cally arranged about their central values, these three means are 

 identical. Actual series of results are rarely quite symmetrical, 

 however, and in such cases the three means may differ. In the 

 accompanying Table, the three forms of mean values of the results 

 of the present series are placed together for comparison. 



Table vi. 



Aiithmetic means, medians, and modes or most prol)al)le values, of the 



composition and properties of cows' milk. 



The figures in the above Table show that the three forms of 

 mean value are very close together for most of the quantities 

 measured. The greatest variation is to be seen in the case of 

 the weight of fat obtained at a milking. The mode of this 

 weight is about 14% less than. the mean. The modes of the per- 

 centaiic of fat and of the weifiht of milk obtained at a milkinii- 



