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Data Analysis with R - Second Edition by Tony Fischetti

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A word of warning

Before we move on, a word of warning: the first part of every regression analysis should be to plot the relevant data. To convince you of this, consider Anscombe's quartet depicted in the following figure:

Figure 9.6: Four datasets with identical means, standard deviations, regression coefficients, and R2

Anscombe's quartet holds four x-y pairs that have the same mean, standard deviation, correlation coefficients, linear regression coefficients, and R2s. In spite of these similarities, all four of these data pairs are very different. It is a warning to not blindly apply statistics on data that you haven't visualized. It is ...

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