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Activity Number:
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189
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Type:
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Contributed
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Date/Time:
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Tuesday, August 7, 2001 : 12:00 PM to 2:00 PM
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Sponsor:
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Section on Physical & Engineering Sciences*
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| Abstract - #300985 |
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Title:
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An Example from Proficiency Testing of the Application of Principal Components to the Estimation of Variance Components in the Mixed Model
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Author(s):
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Stanley Shulman*+
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Affiliation(s):
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National Inst. for Occupational Safety & Health
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Address:
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4676 Columbia Parkway, Cincinnati, Ohio, 45226,
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Keywords:
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Variance Components ; Multivariate Methods ; Interaction
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Abstract:
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A common problem in lab proficiency testing is the estimation of measurement error and of lab to lab variability, when duplicate samples are not available. Since the measurement errors are often assumed to constitute a statistically independent set, the variance-covariance matrix should be the sum of a multiple of an identity matrix (corresponding to measurement error) and a matrix different from an identity matrix . Multivariate statistical methods provide tests that a variance-covariance matrix is of this form. In this paper, these methods are applied to data from the Proficiency Analytical Testing Program(PAT). For these data, variances and covariances are assumed to be approximately proportional to an unknown power of the mean, and various possibilities for the form of the associated variance-covariance matrix are considered. The form depends on the scale on which the analyses are carried out, the possibility that the measurement error and non-measurement error have variances that are not proportional to the same power of the mean, and the dimensionality of the non-identity matrix. Examples are presented from PAT.
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- The address information is for the authors that have a + after their name.
- Authors who are presenting talks have a * after their name.
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