272 COLLECTION OF STATISTICS. 



and 



. . . = total annual yield 

 total area 



Example : 



A working section of 1000 acres contains : 



Block (1) 200 acres with 60 c' average increment 



(2) 100 50 



(3) 200 40 



(4) 500 30 then- 



Mean quality 



200x60+100x50+200x40 + 500x30,,, , 

 1000 



By reduced area is now understood that which would 

 produce, with a uniform quality = Y, the same total yield as 

 the actually existing areas with their varying qualities. It is 

 obtained by applying, in each case, the inverse proportion of 

 that which exists between the actual and the mean quality : 



In the above example : 



Block (1) The proportion is 60 : 40 ; hence the reduced area 

 x is obtained by means of the equation 



A s\ f* r\ r\r\f\ 1 \J\J s\ \)\) orv/"v 



Total . . . = 1000 acres. 

 If now the forest is to be divided into annual coupes of equal 



