What isstandard deviation

Standard deviation is a commonly used statistic in fields like finance, science, and research to indicate how far the data points are spread out from the average, or mean, of the dataset. In simpler terms, it measures the degree of variation or dispersion of a set of values around the average.

What is Standard Deviation?

Standard deviation, represented by the lower case Greek letter sigma (σ) for population standard deviation or the Latin letter s for sample standard deviation, is a measure of the amount of variation or dispersion in a set of numerical data. It tells us how spread out the data is from the average value, or mean.

How is Standard Deviation Calculated?

To calculate standard deviation, first calculate the mean of the data set. Then subtract each data point from the mean and square the result. Add up these squared differences and divide by the number of data points. Finally, take the square root of this resulting value.

The Importance of Standard Deviation

The standard deviation is important because it helps in understanding the statistical significance of the data and can be used to compare data sets. A low standard deviation suggests that most of the data points are close to the average value, while a high standard deviation indicates that the data is more spread out. The standard deviation is frequently used in statistical tests such as hypothesis testing, t-tests, and ANOVA to determine the significance of differences between sample groups.

Frequently Asked Questions (FAQ)

What does a high standard deviation indicate?

A high standard deviation indicates that the data points are widely spread out from the mean and have a larger degree of variability or dispersion.

What is the difference between population and sample standard deviation?

Population standard deviation is calculated using all data points in a specific population, while sample standard deviation is calculated using only a portion, or sample, of the population.


Standard deviation is an important statistical measure that allows us to quantify the variability of a set of data points. Understanding standard deviation is crucial in various fields and can aid in making informed decisions based on statistical analysis.

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