Uniformly balanced repeated measurements designs in the presence of subject dropout
Uniformly balanced repeated measurements designs in the presence of subject dropout
Low, Lewis and Prescott (1999) showed that a crossover design based on a Williams Latin square of order can suffer substantial loss of efficiency if some observations in the final period are unavailable. Indeed, if all observations are missing, the design becomes disconnected. We derive the information matrix for the direct effects of a Uniformly Balanced Repeated Measurements Design (UBRMD) in periods when subjects may drop out before the end of the study, and examine the maximum loss of information. The special case of loss of observations in the final period only is examined in detail. In particular we show that a UBRMD in periods remains connected when some or all observations in the final period are unavailable.
crossover designs, efficiency, missing observations, Williams Latin Squares
235-253
Majumdar, D.
35e559d8-6d40-47d5-b6bc-7a84ac1e01d7
Dean, A.M.
9c90540a-cdf4-44ce-9d34-6b7b495a1ea3
Lewis, S.M.
a69a3245-8c19-41c6-bf46-0b3b02d83cb8
January 2008
Majumdar, D.
35e559d8-6d40-47d5-b6bc-7a84ac1e01d7
Dean, A.M.
9c90540a-cdf4-44ce-9d34-6b7b495a1ea3
Lewis, S.M.
a69a3245-8c19-41c6-bf46-0b3b02d83cb8
Majumdar, D., Dean, A.M. and Lewis, S.M.
(2008)
Uniformly balanced repeated measurements designs in the presence of subject dropout.
Statistica Sinica, 18 (1), .
Abstract
Low, Lewis and Prescott (1999) showed that a crossover design based on a Williams Latin square of order can suffer substantial loss of efficiency if some observations in the final period are unavailable. Indeed, if all observations are missing, the design becomes disconnected. We derive the information matrix for the direct effects of a Uniformly Balanced Repeated Measurements Design (UBRMD) in periods when subjects may drop out before the end of the study, and examine the maximum loss of information. The special case of loss of observations in the final period only is examined in detail. In particular we show that a UBRMD in periods remains connected when some or all observations in the final period are unavailable.
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Published date: January 2008
Keywords:
crossover designs, efficiency, missing observations, Williams Latin Squares
Organisations:
Statistics
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Local EPrints ID: 54763
URI: http://eprints.soton.ac.uk/id/eprint/54763
ISSN: 1017-0405
PURE UUID: e694aab3-7902-46ba-8d3e-2cc42f7bfa5a
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Date deposited: 04 Aug 2008
Last modified: 08 Jan 2022 10:04
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Contributors
Author:
D. Majumdar
Author:
A.M. Dean
Author:
S.M. Lewis
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