The standard deviation is the commonly used measure of variability when working with numeric data. It indicates how much, on average, each score in a set varies from the mean value of that set. It is usually represented by “s” or SD and is indicated as a +/- value. This single value demonstrates how much variability or dispersion is among scores in a set. To calculate the value, we must compute the deviation of each score from the mean and…
Measures of variability, such as the range, variance, and standard deviation, are types of descriptive statistics that complement the measures of central tendency in describing data sets. These measures of variability reflect how scores differ or are spread or dispersed from one another. A more precise definition is the distance or amount a score in a data set differs from the typical score in the set, usually the mean. The three most common forms of variability are the range, variance,…
Descriptive statistics are used to organize, summarize and describe the attributes of a set of data. A set of data, especially numeric data, are often referred to as a distribution. A category of descriptive statistics is those measures that describe a distribution using one measure and can be thought of as describing “middle’ or typical score within a distribution. These measures of central tendency, such as the mean, median, and mode, are typically used as the best summary of a…