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Some Data on the Influence of Attempted Interpolation on the Speed and Errors of Scale Reading.

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This report presents data which indicate the manner in which the speed and errors of scale reading are influenced by a change in reading instruction from Read to the nearest scale mark to Read to the nearest tenth of a scale division. The data were obtained in a short experiment in which 20 subjects read a series of simply designed, straight scales which were graduated every unit and numbered every 10. Their general instruction was to work as rapidly as possible. As compared with readings taken to the nearest unit, readings which are attempted to the nearest tenth of a unit required about one and one-half seconds additional reading time, entailed about 50 more reading errors, and had a larger mean square error. The error increase applied both to gross reading errors and to local errors which resulted in failures to obtain readings correct to the nearest unit. Data extracted from the records of Experiment 4 of the Princeton Laboratory series bear out these results. The data are interpreted to mean that the task of interpolating to tenths of divisions increases the readers likelihood of making systematic errors. Readings to tenths would become superior only if better reading techniques, checking procedures or improved scale designs were developed which would eliminate gross errors.

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  • Human Factors Engineering and Man Machine Systems
  • Test Facilities, Equipment and Methods

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