What is deviation?

Deviation refers to the extent to which a given set of data or observations differs from the average or expected value. In statistics, deviation is often measured in terms of variance or standard deviation, which quantifies how far individual data points are from the mean of the dataset. Deviation can be positive, indicating that a value is higher than the mean, or negative, indicating that a value is lower than the mean. Deviation plays an important role in understanding the spread and distribution of data, and is often used to identify outliers or unusual observations. It is also a key concept in many statistical tests and analyses, such as hypothesis testing and regression analysis, where it is used to assess the significance of relationships between variables.