ZD 



o 



LU 



o 



1600 - 



1200 



> 



< 800 



400 





1 1 M 1 T MO 



U 1 1 IN \J. 







2 1 IJ 1 2 1 1 1 3 



— ^ ^ 











1 1 1 1 1 





10 



20 



30 



40 



50 



60 



70 



90 



100 



DAYS 



Figure 14. — Pieces per productive hour (cumulative) vs. date, unit. 



During 1971, gross data were collected on each of the logged units. This informa- 

 tion included M bd.ft. logged per acre (V), bd.ft. per piece (B) , turns per productive 

 hour, pieces per productive hour, percent productive hours (P) , and costs per M bd.ft. 

 (C) . Table 1 shows these data for the units that were either completed or had sub- 

 stantial volumes of timber removed. The following regression analyses on these data, 

 based on unit averages, explains much of the variation in costs and production. 



Costs in dollars per M bd.ft. were supplied by Boise Cascade's accounting depart- 

 ment. When total yarding cost per M bd.ft. (C) was used as the dependent variable and 

 regressed on average piece size (B = bd. ft . /piece) , the resulting regression equation was 



C = 92.77 - 0.1564B or in metric terms 



C(- ) = 20.50 - 7.639B(^^^^ — ) 

 \,3 'piece^ 



with r2 = 0.5093. 



With volume per acre (\') as tlie independent variable 



C = 83.89 - 3.458V or in metric terms 



m3 



Cf- ) = 18.54 - 0.0683Br^) 

 ,„3 Iia' 



(1) 



C2) 



and the = 0.8339. Multiple regression using piece size and volume jier acre both as 

 independent variables yielded the equation 



C 



101.90 - 0.0920B - 2.834V or in metric terms 



C(^ ) 



3 3 



22.52 - 4.493 -A— - 0.0560(^) 

 piece ha 



(3) 



with an = 0.9831. 



13 



