PHY 1321 Lecture Notes - Lecture 1: Microsoft Excel, Standard Deviation

• School: University of Ottawa
• Department: Physics
• Course: PHY 1321
• Professor: Andrzej Czajkowski

Document Summary

When we have multiple measurements of the same quantity, we use what is called the mean deviation as a first approximation to the error in the mean value. The deviation of each measurement is the difference between that measurement and the mean value | |; where the mean value ( ) is given by . The mean deviation is therefore the sum of the deviations divided by the number of readings or | | . The parallel bars indicate that no account is taken of the sign of the deviation (i. e. , the absolute values are used). This is probably the simplest way of finding the error in a case when a measurement has to be repeated a number of times. However, in most cases, the quantity used is the standard deviation ( ), which is the square root of the mean square deviation: The standard deviation has another definition in which the denominator is replaced by .