In this video I explain one way in which a distribution can deviate from normality, which is skewness. I explain the difference between positive and negative skew, and how these can be seen in histograms, stem and leaf displays, and box and whisker plots. I then discuss the effect of skew on measures of central tendency and consider possible reasons a sample may be skewed and when we can expect a population to be skewed.

For detail on distributions which violate the general mean-median pattern see von Hippel (2005): https://www.tandfonline.com/doi/full/10.1080/10691898.2005.11910556