Measures of central tendency are measures of the location of the middle or the center of a distribution. The definition of "middle" or "center" is purposely left somewhat vague so that the term "central tendency" can refer to a wide variety of measures. The mean is the most commonly used measure of central tendency. The following measures of central tendency are discussed in this text:

Mean

Median

Mode

Trimean

Trimmed mean

For symmetric distributions, these measures are all the same. For skewed distributions, they can differ markedly.