Students are often confused by the term "skew". If a non-symmetric density curve has a tail to the right (higher values of the variable) we say it is skewed to the right. The skew of a density curve has a great effect on the mean. In a perfectly symmetric curve, the mean and median are the same. The median of a density curve is the point on the horizontal axis where a vertical line through the curve will split the area in half (half the area to the right of the line, half to the left.)

How does this compare with the way we calculated the median of a sample in the previous chapter?