Definition
The time interval between the sensory perception of a PHENOMENON and the motor reaction thereto. Personal equation may be either positive or negative, as an observer may anticipate the occurrence of an event, or wait until he actually sees it occur before making a record. This is a SYSTEMATIC ERROR, treated as of the constant type. It is a PERSONAL ERROR, for which the term personal equation is reserved. It is of special significance in OBSERVATIONS of TIME, made to determine CHRONOMETER CORRECTION.