COMPOSITION OF HUMAN MILK IN AUSTRALIA. 185 



is, to all appearances, no more likely to occur than any 

 other, and the values of the results obtained must, on the 

 evidence at hand, all be regarded as equally probable. The 

 only convenient way of summarising such a series of values 

 is to take the arithmetic mean of them all. But the figure 

 obtained by this process cannot be regarded as being likely 

 to be nearer a " true " value of the quantity measured than 

 any isolated result, as in the case discussed above, but is 

 simply a number such that any particular result in the 

 series is no more likely to be above it than below it. 



But in the case of a series of the second kind, there is a 

 value in the vicinity of which the results seem to be more 

 likely to occur than in parts of the series further removed 

 from this value. There is thus a greater probability that 

 any result will fall in the vicinity of this value than any- 

 where else. Such a value may, therefore, be regarded as 

 the most probable value of the quantity which is being 

 observed. 



The values obtained for the percentages of the various 

 constituents in the samples of human milk analysed in the 

 present work have been arranged according to their mag- 

 nitude, as described above, and it has been found that both 

 of these latter types of series are represented among them. 

 In arranging a series of values according to their magnitude 

 for examination in this way, the successive values must 

 be so chosen as to increase by some convenient amount at 

 each step, and in the present case the increment chosen 

 for each step is one-tenth of the mean or most probable 

 value of the series. If the steps chosen be too small, 

 irregularities (not necessarily inaccuracies) in the values 

 of the results obtained will obscure the general trend of 

 the observations, while if the steps be too large, their 

 number will be too few to adequately show the way in 

 which the grouping of the results varies through the series. 



