LLN, le 28/09/05
Dear Robin,
>I am sorry that I still have problem with this rule: the sum of them
>should be zero.
>
>In another email, I saw ... [1] tests for positive differences
>between Activation and "Anything that is not declared", i.e., your
>scans 0 to 9 that are not declared in your vectors.
>In the second case, the sum is also not zero. Should it be invalid?
The contrast I mentionned in the previous mail is not invalid
provided that there is actually something not declared (in the
example, scans 0-9 were not declared, and SPM would thus compare the
scans identified as "Activation" to those 10 scans). If there is
nothing left implicit, then a contrast such as [1 0] should not be
used.
Hope this clarifies,
Mauro.
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Mauro PESENTI
Research Associate, National Fund for Scientific Research (Belgium)
Unite de Neurosciences Cognitives
Departement de Psychologie
Universite Catholique de Louvain
Place Cardinal Mercier, 10
B-1348 Louvain-la-Neuve
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http://www.nesc.ucl.ac.be
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