UNITED STATES DEPARTMENT OF AGRICULTURE 

 7Cy$- FOREST SERVICE, 



intermomtaih forest % rahe experiment station 



0~C DEN 



5 



U T A H , + 7ft^ 



No. 48 



November 1957 



TRUCK LOAD SAMPLE SCALING TO ADJUST COMPANY SCALE * 



Donald W. [Lynch^ 

 Division of Forest Management Research 



DESCRIPTION OF THE METHOD 



A method of sample scaling that adjusts a company's scale to Forest 

 Service standards is proving to be accurate and inexpensive. Since a logging 

 company (or any other purchaser) must scale every load for its own accounting 

 purposes, there is obvious duplication of effort if the Forest Service also 

 scales every load. But since there are certain differences in scaling stand- 

 ards between the Forest Service and most companies and since the Forest 

 Service is required by law to obtain its own measure of all products sold, 

 an independent scale must be made. This paper presents a method for easy 

 preparation of such an independent scale. 



Fortunately, an accurate adjustment of the company's scale can be de- 

 termined from a relatively small sample. The variation between company and 

 Forest Service scales usually is less than the variation in total volume from 

 load to load. For this reason, a smaller sample of truck loads is needed to 

 adjust a company's scale than would be needed to obtain an accurate average 

 volume in conventional sample load scaling. In adjusting a company's scale, 

 every load is scaled by the company, and the total volume is adjusted by a 

 ratio factor obtained by the Forest Service sample scale, as follows: 



Adjusted a I Company's \ I Forest Service scaled volume of sample loads 

 total volume I total volume/ \ Company's scaled volume of the same loads 



Certain obvious precautions must be taken in this sampling process: The 

 sample loads must be selected strictly at random and without the previous 

 knowledge of the company scaler. This assures that the same standard of scal- 

 ing is applied to all loads. If different sized trucks are operating on the 

 sale, the sample should be chosen in a representative fashion, that is, by 

 stratified random sampling. Care must be taken that all loads are accounted 

 for in determining the company's total volume. If loads contain two or more 

 species, volumes of which must be determined separately, the volume by species 



