Improved Operational Testing and Evaluation and Methods of Combining Test Information for the Stryker Family of Vehicles and Related Army Systems Phase II Report (2004) / Chapter Skim
Currently Skimming:
1. Introduction to Combining Information
1. Introduction to Combining Information
Pages 11-16
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 11... ...
Information combining entails more than simply viewing a collection of numbers in a common context. If all the data sets resulting in all the information to be combined were available in their most detailed versions, one could try to view the combined data set within an appropriately wider context.
|
From page 12... ...
If the underlying assumptions are not found to be seriously violated, then formal combination of data usually builds a stronger inference than would be possible otherwise. The most straightforward statistical approach to information combination is the pooling of information from two or more comparable studies.
|
From page 13... ...
This gain is strongest in situations where the sample sizes for the individual data sets are very small. Another example is the case where in the analysis of several sets of reliability data it is assumed, on the basis of appropriate diagnostic tests, that the data sets are distributed according to a Weibull failure time model with the same shape parameter as a previously analyzed set of data but with characteristic life parameters that vary, perhaps in a manner related to study covariates, between the data sets.
|
From page 14... ...
Although apparently minor violations of assumptions made to combine two data sources may, from a purist point of view, result in improper inference, one may sometimes choose a more pragmatic approach. For example, combining data sets that have slightly different means to estimate an assumed common location parameter has the effect of translating any differences in location between the two data sets into an inflated estimate of variability.
|
From page 15... ...
Since the defense acquisition process involves a number of organizations motivated by different and often competing incentives, we also stress the need to use assessment methods that help to ensure unbiased expert opinions. In arguing for this fundamental change to the operational evaluation of defense systems, the panel is aware of its broader nonstatistical implications, which champions of these methods in the defense test and evaluation community will have to consider during implementation.
|
From page 16... ...
Chapter 2 provides simple examples of methods for combining information within the weapons systems test and evaluation context to suggest approaches, explain considerations, and identify potential advantages. Chapter 3 presents more realistic examples of how modeling for combining information can be applied to Army operational test and evaluation, considering the Stryker system at times as a specific application, and discusses implementation issues relating to combining information methods in the context of weapons system testing and evaluation.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.