# Chapter 1. Introduction

In the previous century, the Vienna University of Technology in Vienna enrolled a bachelor study called data engineering and statistics. Basically the content was perfectly related to the nowadays commonly-used term **data science**. Data-oriented lectures in the area of computer science, such as storing and retrieving data, programming, and data security, were in the curriculum, together with applied lectures on statistics, such as multivariate statistics, biostatistics, financial statistics, statistical learning, and official statistics. We had too few students and after a few years the course was canceled. 16 years later, the picture completely changed. New bachelors and masters courses on data science have been developed everywhere in the world over the last few years. Universities have found that they must offer studies on data science, because the industry needs experts on it, but also developments in statistics in recent years have almost exclusively come from an area called **computational statistics**. Statistics is the original form of computing data, and computational statistics takes this to an extreme where methods and tools are developed in a highly data-dependent manner, using and developing modern computational tools. Computational statistics and data science are closely related. Computational statistics covers a broad swathe of data science, exclusive data management, and data security issues. Computational statistics (and therefore also data science) has become very popular since the eighties, and it is very likely the most influential area of statistics nowadays. In the field of computational statistics, not only is new methodology developed, but it is also implemented in software – nowadays almost exclusively in the old but modern **software environment R**.

**Data science** seems like a good term when your work is driven by data with a less strong component on method and algorithm development than computational statistics, but with a lot of pure computer science topics related to storing, retrieving, and handling data sets. It also differs from computational statistics in various aspects. For example, in the area of data visualization also pure process-related visualizations (airflows in an engine, for example) are a topic in data science but not in computational statistics.

Wikipedia defines data science as a field that:

"incorporates varying elements and builds on techniques and theories from many fields, including math, statistics, data engineering, pattern recognition and learning, advanced computing, visualization, uncertainty modeling, data warehousing, and high performance computing with the goal of extracting meaning from data and creating data products."

Data science is the management of the entire modeling process, from data collection, storage and managing data, data pre-processing (editing, imputation), data analysis, and modeling, to automatized reporting and presenting the results, all in a reproducible manner. It is thus also an interdisciplinary study to extract meaning from data with statistics, by using a lot of elements in computer science, as well as general subject-matter skills. In that sense, data science is an extension and continuation of statistics. Data scientists use statistics and data-oriented computer science tools to solve the problems they face.

**Statistical simulation** is an essential area in data science. The core issues of this book are simulating distributions and data sets, Monte Carlo methods for inference statistics, and presenting solutions on computer-intense approaches. This book discusses various areas in statistical simulation, random number simulation, resampling, Monte Carlo methods, statistical theory explained by simulation experiments, agent-based microsimulation, and system dynamics. The aim is to put a book into the hands of readers that explains methods, gives advice on the use of those methods, and provides computational tools to solve common problems in statistical simulation and computer-intense methods.

In this book, the theory is not just explained. The theory is also made understandable with illustrative examples using the R software environment. The reader will get to grips with the R software environment. After getting the background on popular methods in the field, readers will see applications in R to better understand the methods, as well as to gain experience when working on real-world data and real-world problems.

R itself is perfectly suited to carry out simulations. It should be mentioned that the basics of R are not the topic of the book, but advanced data manipulation and advanced visualization tools are shown in R. The reader should therefore not be a complete newbie in R, and if so, should first read a very basic introduction to R.

Readers will get a brief overview of the problems and possibilities of data-driven simulation and resampling methods.