HARVESTING PRODUCTION ANALYSIS 



Regression Analysis 



Harvesting production was analyzed using regression analysis of important variables. 

 Time was the dependent variable. The different independent variables were number of 

 pieces per turn, skidding distance, and volume per turn. A prediction equation is of 

 the form 



Y = b + biX 



o ^ . ■ 



Where b^ is the intercept and b^ is the slope of the line. Table 6 shows the regression 

 coefficients, b and b^, and the F-statistic for all three skidding methods. 

 indicates how important the specific independent variable is in explaining the varia- 

 tion of the equation. The F-statistic was used to test the significance of the 

 regression. 



Cases where the regression is not significant indicate that the data do not fit a 

 straight line, or that there is no relationship between the variables compared in that 

 instance. Scatterplots of the data were examined in these nonsignificant cases. The 

 independent variable did not appear to affect the dependent variable, time. 



Table 6 shows that distance has very little effect on travel time in and out. In 

 this study the range of distances was too limited. However, it does appear that distance 

 affects travel time more for the skidder and tractor than for the horse. Number of 

 pieces per turn had more effect on hook time for the skidder and tractor than for the 

 horse. (This is partially explained by the fact that the horse crew had a helper 

 getting the next drag ready for hooking.) Roundtrip time is more dependent on volume 

 per turn for the skidder and tractor than for horse skidding. 



Table b .- -Prediction equation regression ooeff-Laients, R^, and F for skidding production 



Dep. var. Y 



X 





Skidder 







Horse 







Tractor 





: b 







bl 



R2 



F 



b 







bl 



R2 



F 



b 







bl 



R2 



F , 



Time out 



Dist . 



1.38 



0.006 



0.22 



43.1* 



1.34 



0.001 



0.05 



4.5* 



1.63 



0.006 



0.21 



18.5* 



Time in 



Dist. 



1.06 



.006 



.22 



44.8* 



.78 



.006 



.17 



16.8* 



1.24 



.008 



.20 



17.0* 



Time in 



NP 



2.24 



.02 



.005 



.81 



1.55 



.07 



.02 



2.0 



2.42 



.08 



.04 



3.1 



Hook time 



NP 



1.05 



.54 



.35 



83.9* 



1.50 



. 14 



.18 



17.7* 



.31 



.62 



.72 



175.2* 



Unhook time 



NP 



1.12 



.06 



.03 



4.8* 



.27 



.04 



. 11 



9.4* 



.58 



.15 



.28 



26.0* 



RT time 



NP 



10.8 



.60 



.16 



30.6* 



7.46 



.23 



.08 



7.4* 



6.63 



1.3 



.58 



95.0* 



RT time 



vol /turn 



11.5 



.12 



.15 



27.8* 



7.63 



.04 



.07 



6.2* 



7.11 



.28 



.56 



85.3* 



Y = b^ + biX 



* indicates significance at 0.05 probability level 



RT = round trip 



NP = number of pieces 



12 



