How Do I Add Error Bars to My Plots?
Mathematica offers a number of powerful functions for presenting
experimental error and drawing error bars. The two main ones are
ErrorListPlot in the package
ErrorBar in the package
Both packages ship with Mathematica.
ErrorBar is the much more powerful function,
and it is well
documented in the package MultipleListPlot.
So the discussion here is limited to the simpler ErrorListPlot.