Definition of Variables 



Variables were divided into three classes: dependent variables (measurements of 

 time) , independent variables (factors directly related to the operation of the yarding 

 subsystem) , and coded independent variables (qualitative independent variables with 

 only a few levels). The dependent variables were defined as follows (the abbreviation 

 following the variable will be used throughout this report) : 



1. Travel unloaded (TU) . --Time, in minutes, required for the balloon to travel 

 from the log landing area to the general area of the felled logs. 



2. Travel laterally out (TLO) . --Time, in minutes, required for the choker setter 

 to drag the tagline from a point directly beneath where the balloon stopped to the 

 felled logs. 



3. Hook chokers (HC) . --Time, in minutes, required for the choker setter to hook 

 the tagline to the preset chokers and scramble clear of the travel path of the logs. 



4. Travel loaded (TL) . --Time, in minutes, required for the yarder to yard the 

 load of logs and place them on the landing. 



5. Unhook chokers (UC) . --Time, in minutes, required to unhook the chokers. 



6. Total turn time (TT). --Total time, in minutes, for one complete logging cycle 

 (TT = TU + TLO + HC + TL + UC) . 



The first five dependent variables are the elements from which component models 

 were constructed. The sixth variable, total turn time (TT) , is the dependent variable 

 used in the model for predicting the time required to complete a logging cycle. 



Measurements of time were also taken on foreign elements, delays in the logging 

 cycle due to an event which was not a normal occurrence during the yarding operation. 

 Foreign elements were not included in the analysis as they proved to be random. 



The independent variables were defined as follows (the abbreviation following the 

 variable will be used throughout this report): 



1. Number of logs (NL). --Total number of logs carried on each turn. 



2. Volume (VOL) . --Volume , in board feet (Scribner scale), of the logs carried on 

 each turn. 



3. Weight (WT) . --Weight , in pounds, calculated from measurements of the logs 

 carried on each turn. 



4. Distance (DI). --Slope distance (along the ground surface), in feet, from the 

 landing area to where the balloon stopped to pick up a load of logs. 



5. Slope (SLO).--A decimal number defined as the vertical distance from the 

 yarder to the logs, divided by the horizontal distance from the yarder to the logs 

 (slope is positive for yarding downhill and negative for yarding uphill) . 



6. Lateral distance (LDI).--The lateral distance, in feet, from where the tag- 

 line touched the ground to the choker on the felled logs. 



7. Lateral slope (LSLO).--A decimal number determined by the vertical distance 

 from the ground beneath the tagline to the logs, divided by the horizontal distance 

 from the tagline to the logs. 



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