If the frequency distribution of a data set is more inclined towards smaller or larger values, the distribution is said to be skewed. If data values are skewed to the right, then the distribution is called positively skewed. Conversely, if the plot is skewed to the left, the distribution is called negatively skewed.

For instance, in the middle of a pandemic, the geographical distribution of vaccine coverage may be positively skewed towards populations in the global north countries. However, within any one such country, the vaccine distribution may be negatively skewed towards the percentage of the population, indicating that a significant fraction of the country’s population is vaccinated.

In the case of a skewed distribution, the mean and median also lie more decidedly towards the direction of the skew. However, by definition, the mode peaks at the distribution’s peak.