At the very beginning of a data analysis, we typically have several fundamental questions about our data, such as: How much and what kind of data are available? What are the main characteristics of the data? What types of statistical inferences might the data be suitable for? Exploratory data analysis answers such questions. Expressed differently, exploratory data analysis is about developing a basic understanding of a given dataset. The methods include summary statistics (sample sizes, averages, ...) and statistical graphics (histograms, q-q plots, ...), that is, exploratory data analysis elucidates data by using both numerical and visual means.