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 Analysis and Evaluation RESOURCES I PRIMT I HELP

Review of Some Basic Statistics Concepts

Statistics is the collection and interpretation of quantitative data and the use of mathematics to estimate population parameters. In testing, the analyses of sample data, using statistical techniques, looks for what happened, how well the test article performed vs. some criteria, and makes predictions about future performance. The use of statistics for test design and analysis requires extensive training , beyond the scope of this course . However, testers should nevertheless understand some key concepts and terms, which have been simplified and summarized below and in the following screens.

Basic statistics Concept~ Extensive Training

Descriptive statistics: de frequency dis tribu tions. Ex.

Refreshers on basic statistic concep ts are available as a Con tinuous Learning Module (CLE

istograms, curves, and rd deviation.

Inferential statistics: dra 035), accessible via the DAU Continuous Learning Center as well as other sources. See References ance of the entire

population. for details .

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TST102 Fundamentals of Test Evaluation

Lesson 19 – Analysis and Evaluation RESOURCES I PRIMT I HELP

Review of Some Basic Statistics Concepts, Cont.

Probability is a measure of how likely it is that an event will occur expressed as a percentage. Example: 100% ( 1.0) =event always occurs ; while 0% =event never occurs. Most probabilities of test interest fall somewhere between these two extremes.

Frequency Distribution: is a listing of the values that a variable takes in a sample from a larger population sample. T ypically these values are plotted in some manner. Common ones include:

Norm al Distribution: encountered for many naturally-occurring phenomena. Often called the “bell curve” because of the shape of its probability density curve.

Binomial Dist ribution: encountered when outcomes are measured in terms of event success or failure with only two possible outcomes (e.g., in testing, SRAW launch success or failure ) .