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The mean — more formally the arithmetic mean — is the sum of a set of values divided by how many values there are. It's the most widely used measure of central tendency in statistics, and the foundation for calculations like standard deviation and variance.
The mean is a measure of central tendency — it summarizes a data set with one representative number. There are actually several types of "mean" in mathematics (arithmetic, geometric, harmonic), but unless stated otherwise, "the mean" almost always refers to the arithmetic mean: the sum of values divided by the count. This is the same calculation as what's commonly called the average.
Mean (x̄) = Σx ÷ nThe mean, median, and mode are the three standard measures of central tendency, and each answers a slightly different question. The mean accounts for every value and is sensitive to outliers. The median is the middle value and resists outliers. The mode is simply the most frequent value. Use the mean, median, and mode calculator to see all three at once for the same data set.
Khan Academy has a helpful walkthrough of the arithmetic mean and its properties if you'd like more detail.
Yes, the arithmetic mean and average refer to the same calculation: sum divided by count. Other types of mean (geometric, harmonic) exist but are far less common in everyday use.
A single extreme value can shift the mean significantly, especially in small data sets. Since every value is added into the total, one very large or very small number pulls the mean in that direction.
The mean uses every value in the calculation, while the median is simply the middle value when the data is sorted. The median is less affected by outliers, which makes it more representative for skewed data.
Yes, but be careful: if the percentages come from groups of different sizes, a simple average can be misleading. In that case, a weighted average that accounts for group size gives a more accurate result.