Stat4Ci A sensitive statistical test for smooth classification images.

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1 Stat4Ci A sensitive statistical test for smooth classification images

2 Z=1.64, p=.05 Z=2.35, p=.01 Test Z

3 Pour des images ?

4 Gaussian Random field

5 Seuil non corrigé

6 Bonferroni Correction

7 Exemples Bonf t = 4.5228 Bonf t = 3.5463 RFT t = 4.06

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9 Pixel test

10 Résumé Seulement 2 paramètres –FWHM = taille du filtre de lissage –p = seuil de confiance Comment choisir FWHM ? –Pour détecter un signal donné, le meilleur filtre est un filtre de taille comparable Problèmes –Si le signal est diffus, le pic est faible Solution –Prendre en compte la taille et le Z score. Cluster test

11 t z = 2.5 k = 350 pixels

12 Pixel test t z = 3.30

13 La toolbox p=.05; tC=2.7;% threshold for 2D image (other test) FWHM=HalfMax(sigma_b); [Sci,h] = SmoothCi(Ci, sigma_b); ZSCi = ZTransCi(SCi, mean(vecCi(:)), std(vecCi(:))); [volumes,N]=CiVol(sum(mask(:)),D) [tP,k]=stat_threshold(volumes,N,FWHM,Inf,p,tC,p); tCi = DisplayCi(ZSCi,tC,k,tP,FWHM,p,RFTtest,background);

14 ZTransCi ZSCi = ZTransCi(SCi, mean(vecCi(:)), std(vecCi(:))); In ZtransCi(Ci1, n1, Ci2, n2, sigmaNoise, smoothFilter), –Ci1 = sum of white noise fields that led to a type 1 response (e.g., correct) –n1 = number of type 1 response –Ci2 = sum of white noise fields that led to a type 2 response (e.g., incorrect) –n2 = number of type 2 response –sigmaNoise = standard deviation of white noise –smoothFilter = Gaussian filter used to smooth the classification image

15 stat_threshold [tP,k]=stat_threshold(volumes,N,FWHM,Inf,p,tC,p); –t pixel –k taille minimun –volumes, num_voxels, FWHM –df : Inf –p_val_peak,... –cluster_threshold, –p_val_extent

16 DisplayCi tCi = DisplayCi(ZSCi,tC,k,tP,FWHM,p,RFTtest,background); tsizereselsZmaxxy ----------------------------------------- C[2.70]9700.444.17122129 [2.70]9170.413.95162129 ----------------------------------------- P3.30- p-value = 0.05 FWHM = 47.1 Minimum cluster size = 861.7

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18 tsize resels Zmax x y ----------------------------------------- C[2.70] 970 0.44 4.17 122 129 [2.70] 917 0.41 3.95 162 129 ----------------------------------------- P3.30- p-value = [0.05] FWHM = [47.1] Minimum cluster size = 861.7 t size resels Zmax x y ----------------------------------------- C[2.70] 1787 0.81 5.2 133208 ----------------------------------------- P3.30- p-value = [0.05] FWHM = [47.1] Minimum cluster size = 861.7

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