工程应用数学-统计基础与Statistica软件.ppt

* * * * * * * * * * * * Style is to a large extent personal. Let us look at five graphical versions of the same data in Figure. The graphs show how the downward trend in the average number of bald eagle hatchlings in northwestern Ontario reversed after DDT was banned in 1973. The top graphic (so easily produced by computer graphics) does not facilitate understanding the data. It is loaded with what Tufte (1983) calls Chartjunk — three-dimensional boxes and shading. “Every bit of ink on a graphic requires a reason. And nearly always that reason should be that the ink presents new information (Tufte, 1983).” The two bar charts in the middle row are clear. The version on the right is cleaner and clearer (the box frame is not needed). The white lines through the bars serve as the vertical scale. The two graphs in the bottom row are better yet. The bars become dots with a line added to emphasize the trend. The version on the right smoothes the trend with a curve and adds a note to show when DDT was banned. * * 其结构类似于Excel的工作表，缺省的数据表是10×10的单元格集，可以更改变量（Variable）或观测值（Case）的数量。要注意的是，由于空的单元格要按缺省值计算，故要删除不需要的Case。Variable和Case的删除可以通过EDIT菜单的DELETE命令执行，Variable和Case的增加则通过Format菜单上的Variables和Cases命令执行。在该表中拷贝、复制和粘贴数据等常规操作均与Excel相同。如果要用已有的STATISTICA数据文件或其它程序产生的数据文件，可应用打开命令。STATISTICA可以打开的文件类型包括Excel, dBASE, SPSS, Lotus/Quattro Worksheets等程序产生的文件和扩展名为txt, csv, htm, rtf等文本格式，并以STATISTICA数据文件的格式保存。 * Stattistics6.0的分析结果的默认输出方式是Workbook窗口，包括表格和图形，分析结果的另外一种输出方式是Report方式，这是Statfot公司在Microsoft公司的RTF的文件格式基础上扩展的文件格式，也可以将这种Report文件格式保存为标准的RTF文件格式。 * Example Select “Statistica → Basic Statistica/Tables” * Interpreting the result STATISTICA displays a table of the sample sizes, sample means, and standard deviations for the two samples. A table gives the test statistic is -0.38, with p-value of 0.70, and 88 degrees of freedom. Since the p-value is greater than commonly choose a-levels, there is no evidence for a difference in energy use when using an electric vent damper versus a thermally ac