统计学CH03 英文版.pptVIP

Keller: Stats for Mgmt Econ, 7th Ed Copyright ? 2006 Brooks/Cole, a division of Thomson Learning, Inc. Chapter Three Art and Science of Graphical Presentations Minard’s Famous Napoleonic Chart… Refer to the reprint of Minard’s chart in your text. Many consider Charles Joseph Minard’s original time series chart to be the best statistical graphic ever drawn. Why? He took a two dimensional space and managed to accurate depict five data variables: size of invading army, size of retreating army, geogaphic location, temperature, and of course, time. The multivariate data is presented in such a way as to provide an intriguing narrative as to the fate of Napoleon’s army. Graphical Excellence… Graphical Excellence is achieved when… large data sets are presented concisely and coherently. the message being presented by the chart is clear. the comparison of two or more variables is aided. the substance of the data, not the form of the graph is prominent. there is no distortion of the data and findings. Graphical Excellence… Edward Tufte of Yale describes graphical excellence as… The well-designed presentation of interesting data – a matter of substance, of statistics, and of design. That which gives the viewer the greatest number of ideas in the shortest time with the least ink in the smallest space. Nearly always multivariate, and Graphical excellence requires telling the truth about the data. Figure 3.1 Graphical techniques should be used when there is a large amount of data… Figure 3.2 Here is pie chart that contains only 3 numbers… Figure 3.3 This is a chart that contains only 7 numbers… Figure 3.4 This bar chart that contains only 6 numbers… Graphical Deception… Graphical techniques create a visual impression, which is easy to distort, therefore… It is more important than ever to be able to critically evaluate the graphically presented information. Be wary of graphs without a scale on one axis. Understand the information being presented: absolute values? relative v