Pull-Down Stats

Abstract

P rescient by several decades, T. S. Eliot mused, “Where is the knowledge we have lost in information?” Finding meaning in the huge amounts of data available in virtually all areas of science requires statistical tools. Happily for scientific spreadsheet users, the Numerical Analysis Group (NAG) of Oxford, UK, has ported their standard statistical analysis subroutines (previously available only as C and FORTRAN code libraries) to the menu bar of the Microsoft Excel spreadsheet. Powerful and sophisticated statistical analyses are within the reach of a point and click, placing powerful statistical analyses into the hands of everyday scientists who need it, who have the computer power to use it, and who may not have the time or the expertise to work at the level of software code. After the NAG Statistical Add-In modules are installed, their use in statistical analysis is essentially transparent. As the name implies, they appear as an additional feature of the resident Excel spreadsheet program (Fig. 1). The NAG add-ins may be used within Excel 7.0 or Excel 97, running under Windows 95 or NT on a PC platform. There is no noticeable slowdown in the operation of the Excel program itself when the add-ins are present. The add-in package consists of 51 routines in five categories: Statistical Modeling, Multivariate Methods, Analysis of Variance (ANOVA), Time Series Analysis, and Generalized Linear Models. On selecting the Excel Function Wizard, the user gains access to statistical routines, such as normal distribution; t distribution; χ2 test; linear regression; correlation matrix; time series analysis; autocorrelation; seasonal autoregressive integrated moving average (ARIMA); ANOVA block, row, and factorial; confidence intervals; hierarchical clustering; and discriminants. Operation is simple. The desired statistical function is chosen from a pull-down menu. Arguments are specified by designating the spreadsheet cells that contain the data. In this regard, it is just like using any of the other arithmetic functions that are part of Excel. Output, likewise, fills a designated set of cells. The use of these functions has been streamlined by requiring only problem-specific input data. Optional (default) arguments may be set as needed. Once one of the add-in functions is embedded in a spreadsheet problem, the output cells are updated, continuously and automatically, to reflect any changes in the input cells. The software is available as a CD-ROM or by downloading a 4.5-Mb compressed .zip file from the NAG Web site. Installation proceeds easily with an Installation Wizard included in the setup file. Complete installation requires a software key, provided by NAG to registered users. Ease of use of the software is augmented by extensive online help files, which can be consulted while Excel is running. The online help is searchable by keywords as well as by index. In addition, NAG has provided an animated PowerPoint demonstration tutorial that shows how to access and use the add-in functions, together with an example spreadsheet. The user-friendliness and the power of this software make it a sure winner. It is highly recommended for any spreadsheet user who employs statistics in everyday scientific work. The reasonable price makes it accessible to almost every level of user, including students. Pharm-Eco Laboratories, Lexington, MA 02421, USA. ebellott{at}pharmeco.com