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DISCUSSION: CCU MEN Is ON SYSTEM PRODUCTTVrTY: PEOPLE AND MACHINES Robert C. Williges Nickerson's paper provides an excellent review of human factors implications when considering productivity in the space station. In an attempt to amplify some of his points, I will restrict my comments to the ramifications of productivity as espoused in modern industrial engineering. As a point of departure, I will use the recent text by Sink (1985) on productivity management to discuss topics related to defining, measuring, and improving productivity. WHAT IS PRODUCTIVITY? An the most general form, productivity in industrial engineering is defined as a simple ratio of some quantity of output divided by some quantity of input. ~ ~ From a systems poLnt-of-view, input quantities (e.g., labor, capital, energy, materials, etc.) go through some transformation (e.g., manufacturing, information processing, etc.) to yield an output (e.g., goods, services, waste, etc.) as shown in Figure 1. By comparing the output quantity to the input quantity, one can ~===cs system productivity as a simple ratio. Two implications are readily apparent from this operational definition of productivity. First, pro~uctivi~v is a metric that represents more than just output performance. Output performance relative to input resources. . ∑ ∑ . ∑ . . . It is a measure of Consequently, productivity is out one component of performance and should not be equate] with overall performance. Other related system performance components might include efficiency, effectiveness, innovation, quality, profitability, etc. From a human factors point of view, productivity ha= the potential to serve as one metric for evaluating humans as components in complex space systems. A second implication of the operational definition of productivity is that the ratio metric is based on same def bed unit of analysis. Just as the Bureau of Labor statistics measure of overall national productivity (i.e., Gross National Product, GNP, divided by labor input) is of limited value, an overall measure of space station productivity is limit - . flare must be taken to chose a meaningful level of analysis in assessing productivity in space systems. Foam a human productivity point~f-view, it may be difficult to distir~uish 82
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83 Input Quantity (1) TransformatIon l Productivity (P) = 0 / I ' ~ ~ FIGURE 1 Formic configuration of the productivity metric. Output Quantity (O) productivity from human performance in cognitive tasks until better measures of input resources, cognitive processes, and output measures are available. Productivity does, however, seem to be a viable metric to evaluate larger units of analysis of space-related missions in which the astronaut is considered one cc mponent of the unit of analysis. these larger units of analysis should be considered in terms of the human/machine interface level and above. a _ _ ea a _ _ a ~ For example, the human component ecu He considered an assess mg the prc~uctivi~y of a space station or in assessing productivity of working environments such as intravehicular activities (IVA) at workstations, extravehicular activities (EU\) outside the space station, and comb med IU~ and Elf cperations such as telerobotic activities (Gillan et al., 1986~. In each case, the ratio metric of productivity includes human components along with hardware and software components, and these productivity assessments can be used to evaluate the relative contributions of various components. HoW IS PRO ACTIVITY MEasuRED? Traditionally, both the time dame ~ and the number of component factors measured are considered in maculating the productivity ratio. In the time domain, both static and Dynamic measure= of productivity are used. Static measures are used to Calculate the productivity ratio for a particular point in time; whereas, Dynamic measures are used to evaluate changes in productivity across a designated time unit. Both measures appear to be useful in evaluating the prc~uctivity of the human component ~ space. Static ratios can be used to assess the relative effect of the astronaut in terms of training investment and performance on a particular space mission. Dynamic productivity indices can be used to evaluate changes in team size, allocation of
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84 ta~ks/functions, and return on investments in automation for space missions. Both static and dynamic measures of productivity can vary in their level of complexity depending upon the number of components measured. Sink (1985), for example, suggests three levels of complexity determined by the number of factors used to construct the productivity ratio. He refers to partial-factor, multifactor, and to-factor measures. Partial factor measures include only one component class (e.g., mission specialist); multifactor measures include several component classes (e.g., mission specialist and computer interface); and total-factor measures include all component classes (e.g., mission specialist, computer-interface, fact equipment, documentation_, etc.) included in any particular productivity unit of analysis. Obviously, the simple productivity ratio quickly explodes into a complex, multivariate measurement problem once the unit of analysis and number of factors of measurement increases. Pesearch is napped to build and evaluate complex productivity measurmnent systems for assessing human components of productivity in space missions. HoW CON E ROD ACTIVITY BE IMPROVED? In that productivity is a Trio metric, increased productivity ~st be considered In terms of both input and output quantities are not merely in teens of improver output. Cor~se~ently, productivity improv~nt can be achieved In five ways, as shawn In Table 1, define upon the relationship of He input and output conditions. conditions are s ~ at restric ~ when considering the h ~ n component, all appear to be possible if the unit of productivity analysis includes human, hardware, and software components related to space missions. Mostly, one considers human productivity improvement in terms of human performance improvements as Nickerson suggests in his paper. But the implication of the conditions listed in Table 1 suggests that these potential human performance improvements (in output) must be evaluated relative to the input changes (e.g., increased training, cost of automation, etc.) in order to evaluate the real impact on productivity. , _ ~ Although these ABLE ~ Conditions for Improving Productivity rafter Sink, 1985) Increasing Output 1. Output increases; input decreases 2. Output increases; input remains constant 3. Output increases; input increases at a lower rate Constant Output 4. Output constant; input decreases Decreasing Output 5. Output decreases; input decreases at a more rapid rate
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85 RESEARCH ISSUES Productivity from an industrial eng veering pa ml-of-view provides an important metric for assessing human performance as a systems component in space missions. Human productivity per se needs to be considered in a systems context, and any evaluation of productivity must assess both input and output quantities ~ order to establish a ratio metric. Two general areas of productivity research in space-related missions appear to warrant increased attention. Measuring Productivity Several Measurement issues must be addressed before human productivity assessments of space missions can be made. The appropriate units of analysis for productivity measurement must be specified. Criteria for partial-factor, multifactor, and tot~l-factor measures need to be established and verified. Automated human performance assessment schemes (Williges, 1977) need to be constructed which could then be used for embedded performance measura~.ant, evolutionary operation, empirical modeling, multivariate criteria, and realistic data bases from which theoretical extrapolations could be made to the design of a variety of future space-redated tasks. Improved productivity measu=e~.ant models with sophisticated human productivity parameters need to be developed and validated. Many of these measurement issues can be addressed by current mNltivariate measurement procedures, but each of them will require validation during actual space missions. Improving Productivity Mast of the ra search issues presented in the Nick£rson paper dead mg with performance enhancements can relate to improving human productivity if the antecedent input quantities are evaluated in order to establish appropriate productivity indices. the unit of analysis at the human-machine interface level or above seems to provide the best cpportunities for improved productivity given the characteristics of the productivity metric. Rf search issues raised by Nickerson dealing with workstation design, human input modes, decision aids, and automation are particularly relevant. In fact, many of the remaining topics to be discussed during this symposium are candidate issues that could be evaluated in terms of productivity improvement metrics. CONCLUSION Productivity is an often used and abused term. By accepting the rather straightforward operational definition of productivity as a ratio of output quantity divided by input quantity, I believe productivity holds promise as an important component metric of space station performance which include human, hardware, and software parameters. Before such a
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86 metric is useful, several productivity measurement and productivity enhancement research issues must be addressed. IN - ~ Gillan, D. J., Burns, M. J., Nicodemus, C. L., and Smith, R. L. 1986 The space station: human factors and productivity. Human factors Society Bulletin 29~11~:1-3. S m k, D. S. 1985 Productivity Management: Planning, Measurement and Evaluations Control and Improvement. New York: Wiley WE liges, R. C. 1977 Automation of performance Cement. Pp. 153-168 in Symposium Prcceedings of Productivity Enhancement: Personnel Performance Assessment in Navy Systems. San Diego: Navy Personnel Research and Development Center. .
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