Absolute error of a single measurement: Delta($x_i$) = |$x_i$ - $x_{mean}$|

Mean absolute error: Delta($x_{mean}$) = $\frac{1}{n}$ * sum(|$x_i$ - $x_{mean}$|)

Relative (fractional) error: Delta$\frac{x}{x}$

Percentage error: $\frac{Delta(x}{x}$) * 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.