In a normal distribution, data is symmetrically distributed with no skew. When plotted on a graph, the data follows a bell shape, with most values clustering around a central region and tapering off as they go further away from the center.
Normal distributions are also called Gaussian distributions or bell curves because of their shape.
The mean, or arithmetic mean, of a data set is the sum of all values divided by the total number of values. It’s the most commonly used measure of central tendency and is often referred to as the “average.”
The mode or modal value of a data set is the most frequently occurring value. It’s a measure of central tendency that tells you the most popular choice or most common characteristic of your sample.
When reporting descriptive statistics, measures of central tendency help you find the middle or the average of your data set. The three most common measures of central tendency are the mode, median, and mean.
Variability describes how far apart data points lie from each other and from the center of a distribution. Along with measures of central tendency, measures of variability give you descriptive statistics that summarize your data.
Variability is also referred to as spread, scatter or dispersion. It is most commonly measured with the following:
Range: the difference between the highest and lowest values