Stat-403/Stat-650 : Intermediate Sampling and Experimental Design ...

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Using Excel for Statistics2. Adding to ExcelThe overall impression, from the tips and warnings above, is that Excel is a powerful environment for data manipulation, summary andtabulation. Its graphical facilities, though not covered in detail in this guide are also very strong. It is weaker on the more advancedstatistical methods such as ANOVA and regression. In this section we explore the options that are available to users who need morestatistical capabilities than are available in Excel.The alternatives include writing or commissioning special macros, supplementing Excel's capabilities with an add-in, using a statisticspackage that is available as an add-in, or using a standard statistics package.Macros can be written in VBA (Visual Basic for Applications). The power and ease of use of VBA will be a pleasant surprise to users whohave programmed using languages such as Fortran or ordinary Basic in the past. The complexity will be an unpleasant surprise to thosewho have never programmed and are attracted to the visual simplicity of Excel. We suggest that writing macros is not as daunting as it firstappears and should be considered by users who have repetitive tasks and who need to automate some of the data manipulation tasks, whereExcel is already strong.We provide a short document on our web site for users who would like to see how to write their first macro.We caution against users who wish to write macros to improve on the weaknesses in Excel's statistical capabilities that have beenmentioned above. Writing macros is addictive and can become extremely time-consuming. There is also a danger that the amateur macrowriter will end by "re-inventing the wheel" yet again!Many add-ins have been written to extend Excel's capabilities, providing boxplots, improved regression and so on. These are generally freeor quite cheap and may help the user who just needs to extend Excel's capabilities a little. We provide a short document listing some addinson our web site.There are also some stand-alone statistics packages that can function as Excel add-ins, but our general view is that if they are needed, thenthe user should also investigate combining their use of Excel, with the use of a standard statistics package.Using a statistics package does not mean abandoning Excel. Many users do their data preparation in Excel, and then transfer the data into astatistics package for the analysis. All the standard statistics packages can read Excel files. The results can then be reported directly, ortransferred back to Excel for presentation graphs to be added.3. ConclusionsExcel offers an exciting environment for data manipulation and initial data analysis. Its pivot tables are particularly good for crosstabulationsand summary statistics and provide a powerful tool for basic data analysis. The reliability of more advanced statistical functionsand wizards is variable.There are some areas in which Excel can be used without reservation, such as the hypothesis tests for means, or the probability functions.However, Excel's facilities for analysis of variance or regression analysis have serious problems. Anyone attempting to perform these typesof analysis should be aware of the limitations of Excel and above all of those cases where Excel generates wrong results. For regressionmodelling, analysis of variance and other more advanced statistical analyses it is better to move from Excel to an appropriate statisticspackage.What Pivot Tables doCreating a Pivot TablePivot table - Example 1Making Changes to a pivot tableAppendix - Excel for Pivot Tables25http://www.rdg.ac.uk/ssc/dfid/booklets/topxfs.html (5 of 15) [12/5/2002 21:29:55]
Using Excel for StatisticsPivot table - Example 2What Pivot Tables do* summarise or cross-tabulate data into tables of one, two or three dimensions* can be modified interactively* offer a range of summary statistics* summarise data from various sourcesCreating a Pivot TableTo create a Pivot Table, the data must be in list (database) format, i.e.* records (cases) as rows* fields as columns* first row with field names* no gaps between rowsTo create a Pivot Table from data in a list:* click on any cell in the list or database* click PivotTable Report in the Data menu* follow the PivotTable wizard's instructionsAt Step 1 of the PivotTable Wizard choose* Microsoft Excel or database* followed by Next >Step 2 will look like this ...* If this is OK, confirm the data range by clicking Next >Step 3 is the main step for designing the PivotTable:TipYou can use a name for the range containing the list.26http://www.rdg.ac.uk/ssc/dfid/booklets/topxfs.html (6 of 15) [12/5/2002 21:29:55]
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