Independent Review

Performing Statistical Analysis

Visual Basic Programmer's Journal
May 1999 edition
by Rama Ramachandran

If you're writing Visual Basic programs that perform statistical calculations, don't try to export your data into a third-party statistical package and then re-import it. Total VB Statistics from FMS lets you link to a statistical engine directly from within your VB code. VB has only a few statistical functions, restricted to functions within SQL statements. Sophisticated calculation including regressions, correlations, t-tests, confidence intervals, and group analysis aren't possible.  With Total VB Statistics, you can pass entire recordsets and retrieve customized results to and from its statistical engine. The product, which offers separate versions for VB5 and VB6, comes as an ActiveX DLL you can distribute with your application.  Just instantiate an object based on the DLL's class, set some properties, and invoke the method to perform the calculation. Total VB Statistics integrates neatly into your VB project, and can analyze any Microsoft/Jet Access table or query.  The results of the analysis are placed in an Access table you can manipulate later. 

Total VB Statistics ships with the Scenario Designer, a wizard-like application you use to set up the process of your statistical analysis.  Each analysis can be stored and retrieved as a "scenario" for reuse. You can test each scenario against the data in your tables in design mode and tweak the scenario as needed.  To analyze different types of data based on continuity, you can perform more than 17 [categories of] statistical calculations that fall into three categories: parametric analysis, group analysis, and nonparametric analysis. 

After determining your analysis design in the Scenario Designer, choose a menu option to generate VB code. This code includes all the calls to instantiate an object, set its properties, and invoke the method to perform the statistical analysis.  Simply copy and paste the code into your project.

The Scenario Designer presents you with numerous parameters you need to set; you need a background in statistics or knowledge about the particular function.  Also, Total VB Statistics relies on the Microsoft/Jet Access tables to hold all the scenario information and return the results. A VB program that uses ADO to go directly to SQL Server, for example, must include an Access database and all its support files to make use of the Total VB Statistics functionality.  It would be better if the statistics engine could simply accept a recordset variable for input and return the output as another recordset variable. Another enhancement could be to use a variant array for input/output.*

If you are looking for a small but powerful statistical calculation engine, Total VB Statistics can help. It is flexible and easy to use, and best of all, it writes the code for you.

Rama Ramachandran is Director of Technology with Imperium Solutions, a Microsoft Solution Provider Partner. He designs and develops desktop and online client/server database systems using Visual Basic, Visual InterDev, ASP, Access, and FoxPro. He lives in Stamford, Conn., with his wife Beena and their son Ashish.  Reach him at rama@imperium.com.

*FMS Comments: our design to use Jet tables insures that output tables can be created (such rights cannot be guaranteed against other databases in all cases) and the availability of a workspace for temporary files which are needed for some calculations. There is little or no performance implication because data is retrieved only once. We welcome comments regarding this feature: suggestions@fmsinc.com.

 

Add Statistical Number Crunching. When you click on the Run button in the Scenario Designer, it executes the calculations and presents the results in a table.  It even generates the source code to perform this action from within your VB program.

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