Which of the following is a definition of standard deviation?

Standard deviation is a statistical measure that quantifies the amount of variation or dispersion in a set of data values. It is specifically defined as the square root of the variance. The variance itself is calculated by averaging the squared differences between each data point and the mean of the data points. By taking the square root of the variance, standard deviation brings the measure back to the original unit of the data, making it easier to interpret in the context of the dataset. This is why identifying standard deviation as the square root of the variance provides a clear and precise definition. Understanding standard deviation is crucial in fields that require statistical analysis, such as health sciences, because it allows for evaluating variability and risk in data.