The Human Factor in Projection Microscope Readings of Wool Fiber Diameter

Abstract

It is known that, despite adherence to the rules governing the use of the projection microscope for fiber diameter readings, wide variations occur in the results from different laboratories as well as from different operators. A study has been made of the human factor in this method, using a total of eighteen well-trained female operators in different experiments. It has been found that the microscope or the slide, if used and prepared correctly, cannot account for the variations, but that some operators have significant constant and/or variable bias. It is shown that a correction, for example through read ing a "standard slide" for a variable bias, should preferably not be attempted, but that an operator having such a bias should rather be eliminated by prior tests.