Descriptive statistics summarize features of a data set (sample); hence descriptive statistics analysis aims to summarize a sample rather than use the statistics to learn about the population from which the data sample was obtained. Exploratory Data Analysis builds upon descriptive data analysis by investigating discoveries, drifts, and relationships involving data to support the proposition of hypotheses. Some charts for categorical variables relate the category to a count or percentage. The most important are: bar chart, Pareto's chart and pie chart or pizza chart. The Individual Value Plot helps to compare the distributions of data samples. Many tools present the cumulative empirical distribution of sample data and an associated theoretical cumulative distribution function. The three classical Pythagorean means are the arithmetic, geometric, and harmonic mean. One of the most used statistics to estimate the data sample is the standard deviation.