Errors vs. Mistakes
ERRORS AND MISTAKES
      Now that you know something about measurement errors let us alert (warn) you to the fact that in science you are not allowed to hide your mistakes under the disguise of errors. Mistakes, sometimes also known as human errors, have no place in physics measurements. Examples of mistakes include: reading one number on a mesuring device and recording another, measuring diameter of a cylinder and recording it in a place reserved for height in the data chart, and mixing apples and oranges in general.

ERRORS CANNOT BE ELIMINATED
      All measuring devices (balances ,metersticks, Vernier calipers, micrometers, etc.) have limitations known as leastcounts. For example: leastcounts for a meterstick, a Vernier, and a micrometer are 0.1 cm, 0.01 cm a d 0.001 cm respectively. This means that measurements made by a meterstick will have an error of +-0.1 and measurements made by a Vernier will have an error of 0.01 cm. These errors cannot be eliminated completely because of the limitations of the measuring devices, i.e., results of all measurements have an uncertainty equal to the leastcount of the measuring device used. The uncertainties in the measurements of all the variables in an experiment are divided by the respective values of the variables. All these fractional errors are numerically added and the result provides a range (X+-delta X) withen which the experimental result should fall. A detailed discussion of this point is in Reasonableness of Errors section.