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Statistical Tools Available for Excel Spreadsheets.

A variety of popular NAG Library sub routines can now be accessed as an add-in for Excel without any programming effort required by the user.

Combine the most used Windows spreadsheet application--Excel-with some of the most acclaimed collections of numerical and statistical algorithms--NAG's Fortran and C Libraries--aand make it easy to use and you could provide researchers with some pretty powerful analysis tools.

At least, that's what the people at The Numerical Algorithms Group (NAG), in Downers Grove, Ill., and Oxford, U.K. thought when they recently announced the availability of NAG Statistical Add-Ins.

NAG's Fortran Library has been available for many years and now consists of more than 1,200 user-callable subroutines for mathematical and statistical computations. Similarly, NAG's C Library contains a collection of more than 300 math and statistical subroutines.

Fifty-one of the most popular and useful statistical routines from NAG's Fortran Libraries--mostly from those in the Fortran 77 section, according to David Sayers, a senior consultant at NAG in Oxford, U.K.--are provided in the Statistical Add-Ins via Excel's function wizard. The Add-Ins are organized in the form of four "books" covering simple statistics, multivariate methods, time series analyses, and analysis of variance and generalized linear models. This modular arrangement provides the advantage of being fast to load and providing the user with a single function that doesn't have large overheads.

Most methods are implemented as array functions, making it possible, like other Excel Add-Ins, for the results to be automatically updated on the worksheet when the data items change (provided that Excel's options have not been set otherwise). There is, however, a Microsoft Excel limit, in excess of 5,000, on the number of elements that may be exported from an array function, thereby limiting the volume of data that can be handled in some cases.

The Add-Ins may be used from Excel version 7.0 or from Excel 97 running under Windows 95/NT on a PC platform. Loading the Add-Ins is straightforward, by simply clicking on the "Tools-Add-Ins" menu in Excel. Any of the Add-In routines may be called via the function wizard or directly as you would with a Microsoft Add-In.

Results are returned via a vector of output information which can be placed on an intermediate Excel worksheet. A NAG-specific macro, accessed from the NAG menu, can be used to place references to the output as desired, thus allowing individual selected items from the output produced by a specific NAG routine to be placed anywhere within the user's workbook.

The Statistical Add-Ins were introduced in the U.K. late last year, and "we're constantly looking to improve it," says NAG's Sayers. "We're looking to learn user requirements in this area and will give serious thought to producing additional materials.

NAG expects to offer a free download service to users purchasing the Add-Ins when minor updates are made available.

"In the U.K., we feel the Statistical Add-Ins will be used quite well in academic settings as teaching tools and for setting up instructional templates," says Sayers, "while in the U.S. they will be used in a wider range of industrial settings."

NAG Subroutines Accessible in Excel

* Normal distribution

* t-distribution

* chi square

* F-distribution

* beta distribution

* gamma distribution

* Linear regression

* Correlation matrix

* Durbin-Watson

* Univariate time series

* Autocorrelation

* Seasonal ARIMA

* Transfer function

* Spectral smoothing

* ANOVA block

* ANOVA row

* ANOVA factorial

* ANOVA contrasts

* Confidence intervals

* Factor score

* Distance matrix

* Hierarchical cluster

* Discriminants

* Mahalanobis

* Multidimensional scaling

More than 50 subroutines are included in NAG's Statistical Add-Ins for Excel.

More Info

Numerical Algorithms Group Inc. 630-971-2337
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Title Annotation:NAG Statistical Add-Ins from The Numerical Algorithms Group
Author:Studt, Tim
Publication:R & D
Article Type:Brief Article
Geographic Code:1USA
Date:Feb 1, 1999
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