noun
personal equation
Technical term in psychology and measurement, referring to systematic individual differences in observation or judgment.
天文観測では、観測者ごとの個人誤差を補正する必要がある。
In astronomical observation, it is necessary to correct for each observer's personal equation.
Compound of 個人 (individual) and 誤差 (error, deviation). The term is a direct translation of the English 'personal equation'.