Final answer:
When a variable measured on an interval scale includes outliers, using the median as the measure of central tendency is the most appropriate choice to avoid the skewing effects of outliers.
Step-by-step explanation:
If your variable was measured using an interval scale and contains outliers, you should probably use the median as your average. Outliers can significantly skew the mean, making it an unreliable measure of central tendency in such cases. While the mode is the most frequently occurring value, it may not be as useful if there are not repeated data points or if the data are continuous. The mean is the arithmetic average and can provide a distorted view when outliers are present, so it may not represent the center of the data accurately. Therefore, the median, which is the middle value when the data are ordered from least to greatest, is least affected by outliers and provides a better representation of the central tendency for a data set with such irregularities.