Simple pilot procedures for the avoidance of disconnected experimental designs
Two simple pilot procedures are proposed for avoiding the problem of dealing with a disconnected experimental design. Both procedures should be carried out on the selected design before any experimentation is considered. The first procedure is a check that the suggested design is connected with respect to treatments. This makes use of the information matrix for the model and provides feed-back on a disconnected design. The second procedure specifies which observations are influential in causing a connected design to become disconnected, with respect to any set of parameter effects, if these observations are lost during the experimental period. This specification is found by examining the projection matrix for the model. These pilot procedures are illustrated by several examples.
Keywords: Analysis of variance; Confounding; Connected design; Estimability; Incidence matrix; Information matrix; Linear contrasts; Pilot procedures; Projection matrix; Rank reducing observation sets; Treatment associates
Document Type: Research Article
Affiliations: Royal Holloway, London, UK.
Publication date: 2004-01-01