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Applicazione SPM (Statistical Parametric Mapping) ad immagini ...

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GLM: stima dei parametri<br />

Trovare β che minimizzi<br />

T<br />

y − Xβ<br />

= ε ε<br />

2<br />

La stima ai minimi qu<strong>ad</strong>rati è data da:<br />

ˆ β =<br />

( X<br />

X<br />

)<br />

T −1<br />

Sotto l’assunzione i.i.d. :<br />

ε ~ N(0,<br />

σ 2 I)<br />

Y ~ N(<br />

Xβ,<br />

σ<br />

2 I)<br />

X<br />

T<br />

y<br />

ˆ ε = Y −<br />

Residui<br />

X ˆ β<br />

σ<br />

ˆ 2<br />

=<br />

N<br />

−<br />

T<br />

ˆ ε ˆ ε<br />

rango(<br />

X )<br />

ˆ 2 T − 1<br />

β ~<br />

N(<br />

β,<br />

σ ( X<br />

X )<br />

)<br />

<strong>SPM</strong>-<strong>Statistical</strong> <strong>Parametric</strong> <strong>Mapping</strong> 30

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