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Operations Research, Systems Engineering and Industrial Engineering Commons

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2008

Physical Sciences and Mathematics

University of Nebraska - Lincoln

Standard deviation

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Full-Text Articles in Operations Research, Systems Engineering and Industrial Engineering

Why Divide By (N-1) For Sample Standard Deviation?, Paul Savory Jan 2008

Why Divide By (N-1) For Sample Standard Deviation?, Paul Savory

Industrial and Management Systems Engineering -- Instructional Materials

In statistics, the sample standard deviation is a widely used measure of the variability or dispersion of a data set. The standard deviation of a data set is the square root of its variance. In calculating the sample standard deviation, the divisor is the number of samples in the data set minus one (n-1) rather than n. This often confuses students. This paper offers a quick overview of why the divisor is (n-1) for calculating the sample standard deviation.