Table 4. -Standard errors of ratios for logging residue 

 volumes by net oubio- and board- foof^ measures ^ 

 Arizona and New Mexiao 



Unit of measurement 





Area^ 









Arizona- 



and 



: Arizona 



: New Mexico : 



New Mexico 



minimum top diameter 



(23) 



: (16) : 



(39) 



'Pex'oent 



Cubic foot 13.171 12.975 9.347 



4 inches 



Board foot 17.169 14.796 11.717 

 Variable 



Board foot 16.421 14.115 11.187 



7 inches 



^International 1/4-inch rule. 



^Number of logging operations sampled in parentheses. 



product trees, a slightly different procedure was used. 

 In such cases, product trees were those whose stumps 

 were within a circular plot. All product trees on 

 the plot were measured, and felling and skidding 

 damage assessed within plot boundaries after skidding. 



Data compilation was accomplished by means of a 

 set of computer programs developed especially for 

 these studies. The output included standard errors 

 of the ratios for residue volumes. For example, table 

 4 indicates that the standard error of the cubic-foot 

 ratio in Arizona is ±13.2 percent, and in New Mexico, 

 ±13.0 percent. 



Caution is recommended if estimates shown in this 

 report are to be applied to any subdivisions of Arizona 

 and New Mexico. The amount of residue per unit product 

 can vary widely from one area to another due to several 

 interrelated factors. Among these are: stand conditions 

 (size and soundness of trees, species, stocking, etc.); 

 markets for various species; size and quality of tim- 

 ber; and logging costs and techniques as determined 

 by accessibility, terrain, etc. 



9 



