Errors of interpolation in instrument reading and setting

Abstract

30 subjects made interpolations between marks 10 mm. apart in 3 different situations: (1) reading from a slide rule set by the experimenter to exact tenths, (2) setting the rule to tenths, and (3) reading tenths from Miller cards. Each subject made 324 interpolations in each of the situations. Results showed large individual differences among subjects. In all three methods errors were made less frequently at position 5 than at any other. Readings at positions 1, 2, 8, and 9 showed an inward bias, possibly due to the use of the end lines as reference points. Readings at positions 3, 4, 5, 6, and 7 showed an outward bias, possibly due to the use of an imaginary line at the center as a reference point. (PsycInfo Database Record (c) 2025 APA, all rights reserved)