Analysis Techniques For Man-Machine Systems Design

NATO UNCLASSIFIEDAC/243(Panel-8)TRL 7 -16 -ssoniVolu~me I1nlsstcniuindividual users. The mean rate of use of the different classes of analysis technique is shown inTable 2.1. It was assumed that, for each project, at least one analysis technique would be used ineach of the five stages (Mission Analysis, Function Analysis, Function Allocation, TaskAnalysis, and Performance Prediction). Thus, in theory, the mean rate (i.e., the number in eachcell of Table 2.1) would be at least 1 and the column totals would be 5 or greater. (The totalentries for all projects in any project stage would, therefore, be 165 (33 x 5).)Table 2.1: Mean rate of use of different categories of analysis technique,in five project phases, In 33 projects (total for each category divided by 33)Project DevelopmentPhaseCategory of Analysi A nalysis Planning Preliminary Design Test and MeanTechnique Used of existing now design evaluation overallusagesystems systemsMission Analysis .51 .54 .54 .48 .39 49Function Analysis .7 .97 .97 .9 .48 .80Function Allocation .52 .9 .82 .76 .42 .68Task Analysis 1.96 1.7 1.97 1.94 1.9 1.89PerformancePrediction.9 1 1.18 .88 1.12 1.02Mean across all stages .92 1.02 1.1 .99 .86 .9825. The overall usage rate reported is 98% of the expected value (162 entries out of 165expected, or 4.89 out of an expected mean total of 5.0). This rate is the best estimate, because itdoes not include data from projects which did not use any human engineering analysis technique.In most countries the level of use for all techniques is significantly less than the expected value(from 54% to 78%) but the overall level of use is increased by data from the USA which show alevel of use varying from 121% to 146%, depending on the project phase. This apparentlyhigher level of use may be due to differences in reporting style. Several of the U.S. respondentsreported general company capabilities, rather than use on specific projects. Differences betweenthe expected and actual rates of use of the different categories of analysis technique are highlysignificant (X2 test). Task analyses are reported almost four times more frequently than missionanalyses and three times more frequently than function analyses: these differences are larger thanreported previously, from a more limited survey (Beevis, 1987). The overall usage rate reportedper project phase varied between 87% (test and evaluation) and 102% (preliminary design). Ithad been expected that the usage rates would vary widely across the five project phases, withmost use being made of the analytical techniques for planning new systems and for preliminarydesign. In fact, the differences in reported rates of usage from one project phase to another arenot significant (X 2 test).26. The lower than expected usage rates pose the question of whether the techniquessurveyed are really useful, particularly those for Mission Analysis and Function Analysis. DeGreene (1970) noted that designers and managers tend to resist human factors analysis and thatNATOUNCLAS SIFIED-16-