Random Vs Systematic Error

In experiments sources of error to help explain results. It is important to look at results and determine if they can best be explained in terms of systematic error or random error. To help distinguish between the two consider the following example; the x's represent the location of arrows shot from a bow to the target.

Random and Systematic Error Terminology	Precision and Accuracy Terminology	Target Shooting Example	Explanation	Experimental Design Implications
Low Random Error Low Systematic Error	High Precision High Accuracy		Best Result
High Random Error Low Systematic Error	Low Precision High Accuracy		If the location of the arrows is averaged they are on target. There is some random event (perhaps random air currents) which causes the arrows to miss their target.	Taking more data and averaging the result can improve the precision in this case.
Low Random Error High Systematic Error	High Precision Low Accuracy		There is little random error in these results, but they have a systematic error causing all the arrows to be off target, perhaps the sight is off or there is a constant wind which has not been compensated for.	Taking more measurements could not improve these results. Perhaps the instruments are not calibrated, or perhaps a zero offset error.
High Random Error High Systematic Error	Low Precision Low Accuracy		Both effects are present here.

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