Final answer:
The median is the measure commonly used for income distributions because they are generally skewed.
Step-by-step explanation:
In a symmetrical distribution, the mean, median, and mode are all centrally located close to the high point of the distribution. This means that the median is not the measure commonly used for income distributions because they generally have unequal class intervals, are symmetrical, or bimodal. Instead, income distributions are generally skewed, which makes the median a more appropriate measure.