Design-Expert 7.0 Software Validation Letter

From: Stat-Ease, Inc.
To: Whom it may concern
Re: Validation of Design-Expert® software

Stat-Ease, Inc. routinely tests its software against published studies that exercise specific features of the products. For example, factorial and fractional factorial designs and analyses are compared with those in Design and Analysis of Experiments, Douglas Montgomery, 1997, Wiley & Sons. Response surface designs are tested against those in Response Surface Methodology, Myers and Montgomery, 1995. And finally, mixture designs are matched with examples from Experiments with Mixtures, Cornell, 1990.

During program development, we export data from our products to an independent statistics package to verify the equation coefficients and ANOVA results, for example. Design-Expert® version 6 software (DX6) was tested against Minitab 12.2, Minitab 13.1, Systat 9 and MathCad 2000. Prior to shipment each new version gets tested against a series of data files that rigorously test all aspects of the program. As detailed below, this testing consists of both internal and external testing procedures. Pages 2 and 3 of this document state the files validated, the features that were unique about these files, and the software or textbook used for verification of results. These data sets are available from Stat-Ease, Inc. Design-Expert version 7 software (DX7) has been validated against DX6 output.

Internal
We have incorporated built-in testing for the math engine of our software. We run a series of test suites to exercise various extreme conditions of the program. Results are compared against known answers and differences are flagged for manual examination.

External
Each new version of a software product is also tested using an automated scripting program. Currently we are using Visual Test by Rational. Using these test scripts we can test not only the computational aspects of the program, but the interface as well.

Manual Testing
When specific problems have been fixed between revisions, we revisit those problems and manually try to reproduce them. If we encounter a test set that represents a new problem class, we add it to our automated test suite.

Tryg Helseth
Principal, Stat-Ease, Inc.

Attachment: DX6 Test Tracking Sheet (DX7 has been verified against the DX6 output for these data sets)