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# Calculating error watch

1. My teacher confused me in Chemistry and Physics the other day when discussing how to calculate errors... What are the different types of error you can consider and how can you do this??? I will rep someone for a good explanation, but try and be as clear as possible and if you can offer some example, that would be much appreciated!

-Rob
2. Systematic errors might be due to faulty calibration, limitations in the theory underlying an experiment, sample contamination or instrument drift; they give rise to a uniform and reproducible error in every reading of the same type.

Random errors are due to inaccuracies in the process of measurement, and are unpredictable. Random errors prevent measurements from being identical and arise from random fluctuations in factors such as temperature or electrical noise, or simply from the inability of the experimenter to read a measuring instrument in precisely the same way each time.

The difference is that systematic errors affect the Gaussian distribution by shifting it to the left or to the right, while random errors just affect the shape of the curve.

You can eliminate random errors by running the experiment several times and apply the mean and standard deviation formulae:

x(average) = (sum of all readings of x) / number of readings of x (=n)

standard deviation = sqr ( [ (reading 1 minus x(average) )² + ... + (reading n minus x(average) )² ] /n-1 )

Thus you give the final reading of x as x(average) +- standard deviation

Shall I continue?
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Updated: November 13, 2004
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