Which function is used to determine how widely values are dispersed from their average?

The STDEV function is designed to calculate the standard deviation of a set of values, which directly measures how much the values deviate from their mean (average). When determining how widely values are dispersed, standard deviation provides a clear indication of that variability. A low standard deviation means that the values tend to be close to the mean, while a high standard deviation indicates that the values are spread out over a wider range.

In contrast, the COVAR function measures the covariance between two sets of values, which assesses how much two variables change together but does not directly indicate dispersion from an average. The MEDIAN function finds the middle value of a data set, providing a measure of central tendency rather than dispersion. The AVERAGE function calculates the mean of the values but does not provide any information about how spread out those values are. Therefore, the STDEV function is the appropriate choice for evaluating the dispersion of values from their average.