Answer: c. Measures of variation reveal nothing about the pattern over time.
The measures of variation are the range, interquartile range, variance and standard deviation.
Variance and its square root, standard deviation measure the dispersion of data about the mean. They measure how spread out the data is from the mean.
Range is a measure of variation that shows the difference between the largest and smallest values in the data.
However, measures of variation reveal nothing about the patterns over time. They treat a given data set as a whole and give numbers are applicable for the entire data set.