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# Chapter 2. Basic Data Analysis

We are confronted with data every day. Daily newspapers contain information on stock prices, economic figures, quarterly business reports on earnings and revenues, and much more. These data offer observed values of given quantities. In this chapter, we explain the basic data types: qualitative, ordinal, and quantitative. For now, we will restrict ourselves to univariate data, that is data of only one dimension. For example, if you follow the daily returns of one particular stock, you obtain a one-dimensional series of observations. If you had observed two stocks, then you would have obtained a two-dimensional series of data, and so on. Moreover, the notions of frequency distributions, empirical frequency distributions, and cumulative frequency distributions are introduced.

The goal of this chapter is to provide the methods necessary to begin data analysis. After reading this chapter, you will learn how to formalize the first impression you obtain from the data in order to retrieve the most basic structure inherent in the data. That is essential for any subsequent tasks you may undertake with the data. Above all, though, you will have to be fully aware of what you want to learn from the data. For example, you may just want to know what the minimum return has been of your favorite stock during the last year before you decide to purchase that stock. Or you may be interested in all returns from last year to learn how this stock typically performs, that ...

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