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Unformatted text preview: 1 Confounding What is confounding If two or more effects are confounded, then: the individual effects cannot be estimated only their sum can be estimated More on confounding run 1 A B C AB AC BC ABC mean 1 + + + + + + + + 222 2 +- + +-- +- 122 3 + +- +- +-- 212 4 +- - + +-- + 112 5 + + +- +--- 221 6 +- +-- +- + 121 7 + +- --- + + 211 8 +- - - + + +- 111 2 3 confounding If we use the ABC = +1 half, then A = BC (main effect of A is confounded with BC interaction) B = AC (main effect of B is confounded with AC interaction) C = AB (main effect of C is confounded with AB interaction) 1 = ABC (intercept is confounded with ABC interaction) 2 4 confounding If we use the ABCD = +1 half, then main effects confounded with three-way interactions Example: A confounded with BCD two-way interactions confounded with other two-way interac- tions Example: AB confounded with CD intercept confounded with four-way interaction 1 confounded with ABCD 2 5 confounding If we use the ABCDE = +1 half, then main effects confounded with four-way interactions Example: A confounded with BCDE two-way interactions confounded with three-way interactions Example: AB confounded with CDE...
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This note was uploaded on 01/09/2009 for the course ORIE 312 taught by Professor D.ruppert,p.jacks during the Spring '08 term at Cornell University (Engineering School).
- Spring '08