:orphan: .. _ahelp_3dNormalityTest: *************** 3dNormalityTest *************** .. contents:: :local: | .. code-block:: none Program: 3dNormalityTest * This program tests the input values at each voxel for normality, using the Anderson-Darling method: http://en.wikipedia.org/wiki/Anderson-Darling_test * Each voxel must have at least 5 values (sub-bricks). * The resulting dataset has the Anderson-Darling statistic converted to an exponentially distributed variable, so it can be thresholded with the AFNI slider and display a nominal p-value below. If you want the A-D statistic un-converted, use the '-noexp' option. * Conversion of the A-D statistic to a p-value is done via simulation of the null distribution. OPTIONS: -------- -input dset = Specifies the input dataset. Alternatively, the input dataset can be given as the last argument on the command line, after all other options. -prefix ppp = Specifies the name for the output dataset. -noexp = Do not convert the A-D statistic to an exponentially distributed value -- just leave the raw A-D score in the output dataset. -pval = Output the results as a pure (estimated) p-value. EXAMPLES: --------- (1) Simulate a 2D square dataset with the values being normal on one edge and exponentially distributed on the other, and mixed in-between. 3dUndump -dimen 101 101 1 -prefix UUU 3dcalc -datum float -a UUU+orig -b '1D: 0 0 0 0 0 0 0 0 0 0' -prefix NNN \ -expr 'i*gran(0,1.4)+(100-i)*eran(4)' rm -f UUU+orig.* 3dNormalityTest -prefix Ntest -input NNN+orig afni -com 'OPEN_WINDOW axialimage' Ntest+orig In the above script, the UUU+orig dataset is created just to provide a spatial template for 3dcalc. The '1D: 0 ... 0' input to 3dcalc is a time template to create a dataset with 10 time points. The values are random deviates, ranging from pure Gaussian where i=100 to pure exponential at i=0. (2) Simulate a single logistic random variable into a 1D file and compute the A-D nominal p-value: 1deval -num 200 -expr 'lran(2)' > logg.1D 3dNormalityTest -input logg.1D\' -prefix stdout: -pval Note the necessity to transpose the logg.1D file (with the \' operator), since 3D programs interpret each 1D file row as a voxel time series. ++ March 2012 -- by The Ghost of Carl Friedrich Gauss ++ Compile date = Jun 14 2021 {AFNI_21.1.12:linux_ubuntu_16_64}