ztrans
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— | ztrans [2010/06/11 00:04] (current) – created jochen | ||
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+ | ====== ztrans ====== | ||
+ | ===== Motivation ===== | ||
+ | Under certain circumstances (e.g. data that is arbitrarily scaled and comes from several sources has to be compared), one way to normalize (re-scale) the data is to apply z-transformation (setting the mean of values in the desired dimension to 0 and the standard deviation to 1). | ||
+ | |||
+ | ===== Function reference ('help ztrans' | ||
+ | < | ||
+ | |||
+ | FORMAT: | ||
+ | |||
+ | Input fields: | ||
+ | |||
+ | tc time course data | ||
+ | dim | ||
+ | tp time points (indices of dim to use for normalization) | ||
+ | |||
+ | Output fields: | ||
+ | |||
+ | ztc | ||
+ | zf z-transformation factor | ||
+ | zsh | ||
+ | |||
+ | See also psctrans</ | ||
+ | |||
+ | ===== Usage examples ===== | ||
+ | * z-transforming a single time-course (e.g. of a region or voxel):< | ||
+ | * z-transformation of an entire VTC (ensuring that dimension is 1):<code matlab> | ||
+ | * z-transformation of 4D-NII VoxelData (ensuring that dimension is 4):<code matlab> | ||
+ | * also obtaining the information about the scaling factor and shift:< | ||
+ | * only using values where no experimental condition in an SDM is active:< | ||
+ | tp = all(abs(sdm.SDMMatrix(:, | ||
+ | |||
+ | % apply z-transformation with those as normalization basis | ||
+ | vtc.VTCData = ztrans(vtc.VTCData, |
ztrans.txt · Last modified: 2010/06/11 00:04 by jochen