Skip to main content
Physics LibreTexts

1.1: Interpreting Errors

  • Page ID
    29118
  • \( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \) \( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)\(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\) \(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\)\(\newcommand{\AA}{\unicode[.8,0]{x212B}}\)

    Systematic Error

    • Measurements deviate from the correct value by the same amount each time
    • Errors have a pattern

    Example:  Time on a watch is always 5 minutes ahead of the true time

    Random Error

    • Errors have no pattern 

    Example:  Everyone’s watch shows a different time

    Uncertainty in Measurement 

    • Number ± error
    • It is the amount a number may be off from the correct value

    Example:  Age ±365 days

    Ratio Comparison

    • Shows how two numbers compare
    • Reduced fraction shows comparison

    Example:  

    \[\dfrac{65 \text{mph}}{30 \text{mph}} = \dfrac{2.2}{1}  \text { (Means one speed is 2.2 times faster than the other)}\nonumber \]

    Percent Error

    • Percentage measurements are off from standard/correct value
    • Absolute value

    \[\text {Percent Error}  = \dfrac{\text {Experimental/Measured Value} - \text {Accepted/Theoretical Value}}{\text {Accepted/Theoretical  Value}} \times 100 \% \nonumber  \]

    Contributors and Attributions


    1.1: Interpreting Errors is shared under a CC BY license and was authored, remixed, and/or curated by LibreTexts.

    • Was this article helpful?