Performance Variation among Logging Machine Operators
Excerpts from the Forest Engineering Research Institute of Canada Technical Report #4 entitled "Performance Variation among Logging Machine Operators" by P. Cottell, R. Barth, L. Nelson, B. McMorland, D. Scott. © 1976 Forest Engineering Research Institute of Canada. All rights reserved.
Logging machine operators vary widely in their levels of performance, most noticeably in productivity. Even in situations where conditions of the forest, terrain, and machines are relatively uniform, it is common to observe wide variation among individual operators and crews.
While widely recognized, there is little documentation about the variation among individual operators of mechanized logging equipment. Even less is understood about the sources of this variation, the human and other factors with which it may be associated, or the nature of the relationships involved.
To evaluate the importance of human influences in mechanized logging, a study of 34 operators of tractor-mounted, hydraulic, tree-felling shears examined variation in job performance among individual workers. Fieldwork in North-Central British Columbia from June to December 1973 produced data on a total of 757 shifts of tree-felling activity in 86 identified cutting blocks. There were 6.2 Productive Machine-Hours (PMH) spent in felling activity during the average shift, for a production average of 701 merchantable trees, or 115 trees per PMH. Operators varied from less than 50 to more than 150 trees per PMH in the average production levels.
The analysis showed that about 1/3 of the performance variation was assignable to day-to-day differences within operators, and that about 2/3 of the variation was assignable to differences between operators. Almost none of the variation appeared to be associated with differences between firms.
Interviews and test exercises conducted with the operators provided information on their background, work experience, attitudes, and certain physical characteristics and intellectual aptitudes. When differences in stand conditions were adjusted for (through the variable "number of trees per acre"), the following operator characteristics showed significant association with observed productivity:
- visual (spatial) depth perception
- manual dexterity
- length of experience operating mechanized logging equipment
- motivation
This study of operator performance should lead to improved criteria for the recruitment of logging machine operators who have the potential to become superior operators. Today, selection is often based on minimal information about the candidates, and interpretation is subject to bias. Some good candidates are chosen, but so are many that turn out to be unsuited for the work. Because hiring, de-hiring, and training are costly activities, better criteria that indicate the individual's likely ability to perform the job would help recruiters maximize the percentage of "correct" decisions, i.e. accept suitable candidates and reject unsuitable ones. More efficient selection could then come from better understanding of how the individual characteristics of operators -- physical and mental abilities, background, acquired skills, and interests -- influence on-the-job performance in various mechanized logging occupations.
Simlog note:
The FERIC report used standard techniques in industrial psychology (parts of the Generalized Aptitude Test Battery) to measure depth perception and manual dexterity. Clearly, Simlog's products are much better predictors of what to expect in the woods because they truly simulate forestry machines in action!
Want to learn more? Please contact Simlog.
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