Frelininary office work (cont.) 



Important steps in the operation 



3, Select accuracy standard 



4. Estimate correlation coeffici- 

 ent of checl-: scaled and tree 

 measured volumes 



Key points 



Established by supervisor's office 

 or regional office. 



Based on previous knovjledge from 

 other sales of similar timber, same 

 volume table and same personnel. 

 See iippendix V. For a rough guide 

 to the correlation coefficient refer 

 to the follovdng table: 



Correlation Coefficient Guide 1/ 



Description of situation 



Correlation 

 Coefficient (r) 



Check scale of individual trees agrees 



closely x'.lth tree measuremients or is 



consistently high or lovj by a constant 



percentage 0.9 



Check scale of individual trees 



generally agrees closely, but occasional 



trees differ widely and inconsistently 0.8 



Check scale and tree measurements differ 



without predictable pattern, with one 



volume being too high, the next much 



too low, etc, 0.5 



1/' Select values intermiOdiate to those given in the table for 

 situations which appear to be intermediate. For more pre- 

 cise estimates, use formula given in i\ppendix V. 



5. Estimate ratio of cost of check 

 scaling to cost of tree 

 measuring a tree 



Based on experience or best esti- 

 mate. See page 21 of this publi- 

 cation. 



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