**Neyer Software LLC** announces the release of **SenTest**™ Version 1.0, Sensitivity Test and Analysis software. The software is a full function Windows^{®} based test and analysis program for conducting and analyzing Sensitivity Tests. This software replaces a number of separate DOS programs which have been in use since 1988. The software allows the user to efficiently choose test levels using the Neyer D-Optimal test method and to analyze the results of the tests using the Likelihood Ratio Test method. These techniques are widely used in a number of industries. They are the methods of choice for testing explosive components for the aerospace, automotive airbag, and military markets. They are the prefered method of the OEDC Guidelines for testing of chemicals. Testing material for fracture toughness and analysis of the effects of brain pressure on stroke are other applications.

The experimenter specifies initial guesses for the parameters of the distribution. **SenTest**™ then guides the user by picking the stimulus levels. The experimenter tells the software whether the specimen responded or failed to respond to the stimulus, and **SenTest**™ then picks the next stimulus level.

In addition to picking the test levels, **SenTest**™ also contains a variety of analysis tools to analyze the results of the test. Any combination of these analysis views can be selected at any time, including during the performance of the test. The analysis is performed using the utilizing the likelihood ratio method. This method has been shown to produce more reliable confidence regions than the older methods. These analysis tools display the results on the analysis in a total of 6 different analysis views. These are the numerical analysis, history plot, probability plot, contour plot, multi contour plot, and different populations.

**SenTest**™ uses the well established Neyer D-Optimal test procedure that utilizes knowledge of ** all** of the past responses in order to more efficiently choose stimulus levels. This is the same method as the earlier DOS program Optimal. Because it continuously refines the knowledge of the parameters of the population, the procedure used by

In addition to using the Neyer D-Optimal test, **SenTest**™ will also chose test levels according to the (Original) Neyer Test, Bruceton Test, Robbins-Monro Test, Langlie Test, and Adaptive Langlie Test methods, depending on the options ordered. These test methods are included for historical purposes only and should not be used if efficient testing is required. **SenTest**™ includes the functionality of the following DOS programs: Bruceton, Langlie, OldTest, Optimal, and Sensit.

The **Bruceton test** was developed during the 1940s. It was developed, not as an efficient test method, but rather a method which allowed easy analysis of the tests results. The **Bruceton test** uses a starting point and a fixed step size. The efficiency of the test is critically dependent on the step size chosen.

The**Robbins-Monro test** was developed during the 1950s. It was developed to "home in" on the mean value. The **Robbins-Monro test** uses a starting point and a decreasing step size. If the starting point is not chosen properly, or if the initial step size is too small, the test could waste many samples getting close to the mean.

The**Langlie test** was developed during the 1960s. It was developed to be a less parameter dependent test than the Bruceton test. With the advent of electronic computers, the restriction on ability to perform analysis that motivated the Bruceton test test was no longer an issue. The **Langlie test** uses a lower and upper limit and averages the last test with a previous level.

The**Adaptive Langlie test**, developed during the 1970s, is, as the name implies, an adaptation of the original Langlie test. It was developed to overcome the problem of specification of one test limit too close to the mean value. The test protocol is the same, except that the levels shift up if a test level near the upper limit results in a failure, with a similar shift down if a test level near the lower level results in a success.

The original Neyer test was developed during the late 1980s. The motivation was to design a test that would use knowledge of all of the test results to pick the test levels most efficiently. It was further refined and became known as the Neyer D-Optimal test (developed in the 1990's). With the advent of computers in the laboratory, it was finally possible to perform the difficult calculations needed to choose as the test level that one level which would provide the most information. The Neyer D-Optimal test uses a lower and upper guess for the mean and a guess for the standard deviation. Unlike the Bruceton test and Langlie test, the Neyer D-Optimal test is almost completely independent of the experimenters guess for the parameters.

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The original Neyer test was developed during the late 1980s. The motivation was to design a test that would use knowledge of all of the test results to pick the test levels most efficiently. It was further refined and became known as the Neyer D-Optimal test (developed in the 1990's). With the advent of computers in the laboratory, it was finally possible to perform the difficult calculations needed to choose as the test level that one level which would provide the most information. The Neyer D-Optimal test uses a lower and upper guess for the mean and a guess for the standard deviation. Unlike the Bruceton test and Langlie test, the Neyer D-Optimal test is almost completely independent of the experimenters guess for the parameters.

The primary analysis method that **SenTest**™ uses is the likelihood ratio method. This method of analyzing sensitivity tests can be used to analyze the results of any sensitivity test. It is more general than the test specific methods that had been developed to analyze the results of Bruceton and other tests. Unlike any other known analysis method, it can also be used to analyze the results of tests where there is no unique estimate of the standard deviation (no overlap of the mixed test results).

In addition to performing the analysis using the likelihood ratio method, **SenTest**™ will also analyze tests using the ASENT (asymptotic), Bruceton Analysis, and Langlie analysis methods, depending on the options ordered. These analysis methods are included for historical purposes only and should not be used if reliable analysis is required. All of the analysis methods with the exception of different populations can be performed with these alternative analysis methods. **SenTest**™ includes the functionality of the following DOS programs: ASENT, BrucAnal, ComSen, LangAnal, MuSig, PlotSen, and ProbPlot.

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