3. The tractor was much slower than the skidder. The average one-way skid was 

 only one-third as far, but required 75 percent of the time taken by the skid- 

 der. Difference in skidding distance on two areas of similar configuration 

 and size was due to the rubber-tired skidder making only three decks and the 

 tractor stringing out the turns along both long axes of the area. 



4. Due to larger residue size and a shorter one-way skid on Danby Ridge, the 

 tractor moved approximately the same cubic foot volume per hour as the rubber- 

 tired skidder moved on Lee Creek. 



5. The skidder was worked far below capacity. The operator was unable to add 

 enough chokers to work his machine efficiently. The tractor worked at or near 

 capacity much of the time. 



6. Because of its size the skidder crushed and broke more material than the small 

 tractor broke at Danby Ridge. 



Regression analysis . --Regression equations of the form Y = bp+b-^X were calculated 

 for each of the independent variables thought to influence some dependent production 

 element. The t-statistic was used to test the hypothesis that a linear relationship 

 exists between the two variables considered. All tests were done at the 95 percent 

 confidence level. A linear relationship was shown to exist in many cases. Looking at 

 the R 2 value makes production variation more meaningful. R 2 indicates the proportion 

 of variation in \ explained by X. For example, an average of 40 percent of the varia- 

 tion in time out (table 9) is explained by distance. The results for other production 

 elements are shown in table 9. 



Table 9. — Relogging production regression coefficients 









Danby Ridge 







Lee Creek 





Y 



: X 



: b Q : 



b l : 



R2 : 



t-test 



: b Q : 



b l : 



R2 : 



t-test 



Time out 



dist. 



0.38 



0.007 



0.38 



* 



0.63 



0.005 



0.42 



* 



Time in 



dist. 



.59 



.005 



.21 



* 



.33 



.004 



.43 



* 



Time in 



turn vol. 



.65 



.01 



.14 



* 



.94 



.005 



.009 





Time in 



no. logs 



.88 



.02 



.001 





.64 



.07 



.03 





Hook time 



no. logs 



1.22 



.46 



.14 



* 



1.58 



.37 



.17 



* 



Bunch time 



no. logs 



.08 



.71 



.33 



* 



.87 



.03 



.006 





Unhook time 



no. logs 



.50 



.27 



.13 



* 



.54 



.07 



.07 



* 



RT time 



no. logs 



5.64 



.99 



.08 



* 



5.87 



.60 



.16 





RT time 



turn vol. 



7.34 



.03 



.02 



* 



9. 16 



.015 



.006 





Y = b 0+bl X 

 * Indicates 



that on the 



basis of 



the data 



, a linear relationship 



exists 



between 



the two 



variables (t-test done at the 95 percent level) . 



17 



