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ŠUMARSKI LIST 1-2/2020 str. 42     <-- 42 -->        PDF

Spinelli and Magagnotti 2011). Today, because of the developments in engine and hydraulic technologies, farm tractors modified for performing forest operations potentially provide higher production rate. In addition, well trained operators with sufficient experience, knowledge and skills are the key for high productivity in harvesting operations (Enache et al. 2016).
Statistical models – Statistički modeli
According to the Pearson correlation test results, it was determined that there was a significant relationship between the distance (X4) and the total time (Y) at the 99% confidence level (p: 0.00, p <0.01) for both methods (Figure 3). There was no significant relationship in the 95% confidence interval (p> 0.05) between the variables of diameter (X1) (p: 0.352), length (X2) (p: 0.974) and volume (X3) (p: 0.635) and total time (Y) for uphill winching. There was a significant relationship between the volume (X3) (p: 0.045) and the total time (Y) for 95% confidence level (p <0.05) for skidding.
As a result of comparing the possible combination of decision variables, the best linear model was considered by using corrected Akaike information criterion (AICc), Bayesian information criterion (BIC) and R2. Then it was decided to add all of decision variables (X1, X2, X3 and X4) in the model. The R2 values of the regression models of uphill winching and skidding on skid trail were found to be 0.896 (AICc: 51.46, BIC: 56.21) and 0.980 (AICc: -31.43,