Sources of error.

Previously we discussed about the importance of precautions in scientific process. Now, we look at the factors that deny us from obtaining the most accurate result possible.

Like a game of chess, mere knowledge of the openings are not enough. A friend of mine once told me that he never thought endgame knowledge was necessary because he never got to one. I think that the reason he never got to one was because he didn't know anything about the endgame.

Similarly, in an experiment, identifying the sources of error is of paramount importance as it allows you to learn from your mistakes.

(Note: Systematic errors are too easy to identify and therefore will not be covered.)


Now, amongst the common sources of errors we have:

-Uneven heating. This might be caused by a flickering flame, or failing to ensure that all sides get heated evenly. This can be averted by using a water bath, or removing the factors that cause the flame to flicker. (i.e. air movement)
-Overheating. To a minor degree, after the flame is switched off, the temperature of the reactants might get heated further due to the heated apparatuses.
-Limiting factor of labeled mass/weights. This is when a weight's actual mass differs from what that is stated. I'm afraid this factor lies out of our hands. Therefore it is important to get the highest quality weights for maximum accurancy.
-Resonance. In every oscillating system, students tend to overlook resonance. Engineers themselves learned their lesson the hard way when resonance resulted in the 1940 collapse of "Galloping Gertie," the original Tacoma Narrows Bridge. (This example is not 100% accurate, please view the source for more info.)
-Electromagnetic interactions between equipment.
-Calibration. Instruments must be checked against a known, precise, standard and adjusted to be as accurate as possible.

Sources: http://en.wikipedia.org/wiki/Resonance#Failure_of_the_original_Tacoma_Narrows_Bridge