Steady state workload is determined through a variation on traditional time and motion studies, which Beville refers to as job sampling. Job sampling data serves three different purposes. First, it delineates current operator workload characteristics. Second, the data can be used to project future state loading for the reorganized positions. Third, the data provide a benchmark to evaluate the impact of future changes.
To perform job sampling, operators are observed in two four-hour time increments, one during peak workload and one during a lower workload period. The four-hour increment is used to capture the variety of activities that can occur during an operatorís shift. One of the many advantages of job sampling over other techniques, such as rating scales, is that it is based on actual, observed operator tasks and behavior. Reliability checks on the technique show 94% reliability.
The primary output of job sampling is the volume of work that must be performed by operations personnel. Histograms of the percentage of time spent on different tasks (such as administrative or operational tasks) are created for each sample or position (click here for an example). The results are compared to job samples in Bevilleís database of more than twelve hundred operating positions, and these comparisons can be based upon job type, unit type, or many other variables. These comparisons help pinpoint the areas that are in need of improvement and can show when it is necessary to reduce or increase a position's workload.
In addition to the volume of work that must be performed, job sampling provides objective data on a variety of operator activities. For board operators, sample data can indicate CRT usage, displays viewed, and control actions taken. For all operators, communication frequency and patterns are captured, along with such activities as maintenance interaction and operational requirements.
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The dates for this year's Fall meeting for the Center for Operator Performance will be announced soon. For more information, please contact Lisa Via. Guests are always welcome!
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David Strobhar's book, "Human Factors in Process Plant Operation," is now available in both hardcover and Kindle e-book.
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