<P> That median is the value separating the higher half of a data sample, a population, or a probability distribution, from the lower half . For a data set, it may be thought of as the "middle" value . For example, in the data set (1, 3, 3, 6, 7, 8, 9), the median is 6, the fourth largest, and also the fourth smallest, number in the sample . For a continuous probability distribution, the median is the value such that a number is equally likely to fall above or below it . </P> <P> The median is a commonly used measure of the properties of a data set in statistics and probability theory . The basic advantage of the median in describing data compared to the mean (often simply described as the "average") is that it is not skewed so much by extremely large or small values, and so it may give a better idea of a "typical" value . For example, in understanding statistics like household income or assets which vary greatly, a mean may be skewed by a small number of extremely high or low values . Median income, for example, may be a better way to suggest what a "typical" income is . </P>

What is the purpose of median in statistics