STATISTICAL MATERIAL 



17 



of maturity of flocks and herds of animals requires care in com- 

 parative enumerations ; a million sheep, three-quarters of which are 

 full grown, are clearly of greater value as immediate potential meat 

 producers than a million sheep, three-quarters of which are lambs. 

 The same care is also necessary in comparing estimates for different 

 countries ; a herd of low-grade Brazilian stock, for example, each 

 yielding, say, 400 Ibs. of marketable meat, cannot be regarded as 

 having the same unit value as a herd of English high-grade beef- 

 cattle, each of which yields, say, 800 Ibs. On the other hand, it 

 is to be noted that, as a rule, any speeding up of the turnover from 

 a given number of meat -producing animals entails an increase in 

 the numbers reserved as breeding-stock. 



Some caution is equally necessary in considering prices, which 

 cannot be taken as they stand, without reference to changes in 

 the general level of prices. This level, as shown by index numbers 

 compiled in different countries, moved steadily downwards from 

 about 1871 to about 1895, and since then has moved steadily 

 upwards with a fairly rapid rise from 1908 and a startling rise since 

 the outbreak of the present war. In dealing with animal food 

 prices, it seems reasonable to note deviations from the general 

 level, whether upwards or downwards, rather than to consider 

 these prices as representing essential changes by themselves. The 

 numbers thus obtained may be called differential index numbers. 

 Unless some such method is followed, undue weight may be given 

 to the changes in the price levels of meat and dairy produce, owing 

 to the fact that the cost of these articles forms a relatively high 

 proportion of the expenses for the total dietary. 1 The following 

 table, compiled from the Board of Trade Index Numbers of Retail 

 Prices in London, may serve the purpose of illustration. 



The rise in the Index Numbers of cereal foods and potatoes may 

 be taken as representing the increase in the general level of the 

 prices of the simple staple food materials, and the differences 

 between these numbers and those of any commodity or group of 

 commodities, such as meat or dairy produce, represent more 

 exactly the true changes in the price-level of that commoditj'. 

 These differential index numbers appear in the table above in a 

 column next to the index numbers of the commodities. It will 



1 Meat and meat-products account for more than one-third of the total food 

 expenditure of the average European and American family, while the addition 

 of dairy products makes the combined cost well over one-half of the total. 



