• When reporting any measurements, be sure to list the best value and the uncertainty, in the form:

• There are two kinds of errors: systematic and random.  You cannot find systematic errors unless you have extra information. Random errors can be estimated (eyeballed) if you have only measured the quantity one time, or calculated if you have measured the value many times.
  
• If you have measured a quantity only one time, you must estimate the error by determining the range in which you are confident the value lies.
• If you have measured a quantity many times, then you should use statistics to determine the best value and the uncertainty.  The best value is the average.  The uncertainty in the average is the standard deviation of the mean (SDM).

• If you are adding, subtracting, multiplying, dividing, or otherwise doing an algebraic operation on your data, you must propagate uncertainties.  The rules are:

Addition and Subtraction:

If your equation is z = x + y or z = x - y, the error in z is:

Multiplication and Division:

If your equation is z = xy or z = x/y , the error in z is:

Powers:

If your equation is z = xⁿ y^m, the error in z is: