++ 3dTcorrelate: AFNI version=AFNI_2011_12_21_1014 (Dec 16 2015) [64-bit] Usage: 3dTcorrelate [options] xset yset Computes the correlation coefficient between corresponding voxel time series in two input 3D+time datasets ‘xset’ and ‘yset’, and stores the output in a new 1 sub-brick dataset.
Options:
- -pearson = Correlation is the normal Pearson (product moment)
- correlation coefficient [this is the default method].
- -spearman = Correlation is the Spearman (rank) correlation
- coefficient.
-quadrant = Correlation is the quadrant correlation coefficient.
- -ktaub = Correlation is Kendall’s tau_b coefficient.
- ++ For ‘continuous’ or finely-discretized data, tau_b
- and rank correlation are nearly equivalent.
- -covariance = Covariance instead of correlation. That would be
- the pearson correlation without scaling by the product of the standard deviations.
- -ycoef = Least squares coefficient that best fits y(t) to x(t),
- after detrending. That is, if yd(t) is the detrended y(t) and xd(t) is the detrended x(t), then the ycoef value is from the OLSQ fit to xd(t) = ycoef * y(t) + error.
- -polort m = Remove polynomical trend of order ‘m’, for m=-1..9.
- [default is m=1; removal is by least squares]. Using m=-1 means no detrending; this is only useful for data/information that has been pre-processed.
- -ort r.1D = Also detrend using the columns of the 1D file ‘r.1D’.
- Only one -ort option can be given. If you want to use more than one, create a temporary file using 1dcat.
-autoclip = Clip off low-intensity regions in the two datasets,
- -automask = so that the correlation is only computed between
- high-intensity (presumably brain) voxels. The intensity level is determined the same way that 3dClipLevel works.
- -prefix p = Save output into dataset with prefix ‘p’
- [default prefix is ‘Tcorr’].
Notes: * The output dataset is functional bucket type, with just one
sub-brick, stored in floating point format.
the results will not be identical to using FIM or FIM+ to calculate correlations (whose ideal vector is not detrended).
in a dataset xset with a single 1D time series file.
http://en.wikipedia.org/wiki/Pearson_product-moment_correlation_coefficient
http://en.wikipedia.org/wiki/Spearman%27s_rank_correlation_coefficient
http://en.wikipedia.org/wiki/Kendall_tau_rank_correlation_coefficient
– RWCox - Aug 2001
++ Compile date = Dec 16 2015