How to evaluate the error
When measuring any values may occur error, that is, the value obtained may differ from the real. Note the error, it estimates indicate the precision with which it was made, or another dimension.
You will need:
pen, paper, measurements
Instruction how to evaluate the error
First of all, it should be understood that there are two types of errors: absolute and relative. The first is the difference between the amount received and the exact value, the second - the ratio between the absolute error and the exact number. In physics, without assessing the magnitude of the error is considered to be unknown.
Make sure you have not made a mistake in the measurements, records from the unit, the calculations, thus eliminating the gross error. They are unacceptable.
Make any necessary adjustments. For example, if one is not necessary to divide the scales at the zero point, it must be considered in all subsequent calculations.
Make sure you know all the systematic errors. The latter may be due to malfunctioning of the device, they are generally listed in the data sheet of measuring equipment.
Measure the random error. This can be done by means of different formulas, for example, using the standard formula quadratic error.
Compare with systematic random error. If the first over the second, it should be reduced. This is achieved by repeated measurements of the same magnitude.
Find the true value, for which the arithmetic mean of all the calculations made.
Determine the confidence interval. This is done according to the formula of calculating the confidence interval using the Student's coefficient.
Find the absolute error in the formula: the absolute error is equal to the square root of the sum of random error in the square and systematic error in the square.
Find the relative error (formula given in paragraph 1).
Record the final result, in which x is obtained by measuring the number of plus / minus error.