So which values would be the outliers? An outlier situation: I think the mean is usually preferred in these situations because the value of the mean can be misrepresented by the outliers. Of course, it will depend on how powerful the outliers are. If they don't significantly change the mean, using the mean as the measure of central tendency will usually be preferred. I believe If the data set is perfectly normal, the mean, median and mode are equal to each other (i.e., the same value). An important property of the mean is that it incorporates all the values in the data set as part of its calculation. That is, it would be the value that produces the lowest amount of error from all other values in a data set. In addition, the mean would be the only measure of central tendency where the sum of the deviations to each value from the mean will always equal zero. When not to use the mean: The mean has one main disadvantage, it is mainly susceptible to the influence of outliers. Values unusually compared to the rest of the data set by either being small, or large in its numerical value. An example of what I'm talking about would be to review the wages of staff at a retail store: Staff 1 2 3 4 5 6 7 8 9 10 Salary 15k 18k 16k 14k 15k 15k 12k 17k 90k 95k The mean salary for these ten staff members is 30.7k. Now, inspecting the raw data would suggest that the mean value may not be the best way to accurately demonstrate the typical salary of a staffer, as most employees have salaries in the 12k to 18k range. The mean is skewed by the two larger salaries. So, in this situation, we want a better measure of central tendency. I think taking the median would be a better measure of central tendency here. The mean is the arithmetic average, and it is probably the measure of central tendency that we are most familiar. Calculating the mean is pretty simple. We just add together all the values and divide by the number of observations in the dataset. The calculation of the mean incorporates all the values in the data. If you change any value, the mean changes