Can You Explain The Errors Of Measurement?

ERRORS OF MEASUREMENT:
Experience has shown that a continuous variable can never be measured with perfect fineness because of certain habits and practices, methods of measurements, instruments used, etc. the measurements are thus always recorded correct to the nearest units and hence are of limited accuracy. The actual or true values are, however, assumed to exist t. For example, if a student's weight is recorded as 60 kg (correct to the nearest kilogram), his true weight in fact lies between 59.5 kg and 60.5 kg, whereas a weight recorded as 60.00 kg means the true weight is known to lie between 59.995 and 60.005 kg.  

Thus there is a difference, however small it may be between the measured value and the true value. This sort of departure from the true value is technically known as the error of measurement.  In other words, if the observed value and the true value of a variable are denoted by x and x +  respectively, then the difference (x + ) – x, i.e.  is the error. This error involves the unit of measurement of x and is therefore called an absolute error. An absolute error divided by the true value is called the relative error. Thus the relative error , which when multiplied by 100, is percentage error. These errors are independent of the units of measurement of x. It ought to be noted that an error has both magnitude and direction and that the word error in statistics does not mean mistake which is a chance inaccuracy.