Absolute error of a single measurement: Delta(x_i) = |x_i - x_mean|

Mean absolute error: Delta(x_mean) = (1/n) * sum(|x_i - x_mean|)

Relative (fractional) error: Delta(x)/x

Percentage error: (Delta(x)/x) * 100%

Example: If x_mean = 5.0 cm and Delta(x) = 0.1 cm:

• Absolute error = 0.1 cm
• Relative error = 0.1/5.0 = 0.02
• Percentage error = 2%

True value: In practice, the mean of repeated measurements is taken as the best estimate of the true value.