Time of day impacts on machine productivity and value recovery in an off-forest central processing yard

New Zealand Journal of Forestry Science

Table 5 Regression model for processor volume productivity (m ³ h ⁻¹ )

Variable¹	Coefficient	Standard error	t-statistic	p-value
Intercept	79.1	2.8	28.0	<0.00001
Stem size	19.3	1.2	15.8	<0.00001
Group C operators	−57.3	2.9	−19.5	<0.00001
Group D operators	−41.4	2.4	−17.0	<0.00001
Total degrees of freedom		F statistic		Adjusted R Square
2491		186.3		0.182

¹Stem size is the average stem size (m³) processed during each hour. Group C and Group D operators were indicator variables for single operators whose productivity was different from members within other groups, but not with members in the same group. Note that the default operator value was when two or more machines processed stems within the same hour.