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Title: Stats question (re: Fisher Transforms and Spatial Smoothing) Post by: bb113 on July 19, 2012, 03:20:40 AM People here have been helpful in the past with questions like this, and I have spent all day trying to figure out what to do but could find no answer.
I have a matrix of pearson's R data that I wished to smooth using a gaussian kernal and use to generate Z-scores from which I will then determine a region of interest. The smoothing does improve the signal to noise ratio but I think the z-scores are being suppressed due to the smoothing process. When I perform the fisher transform (ie R->Z conversion) on the smoothed data the standard deviation is less than what would be expected from a set of pearson's R values, which I think may be invalidating the Z-scores. My solution was to "adjust" the Z scores of the smoothed data by multiplying every value of the matrix by the ratio of stdev(Data)/stdev(SmoothedData)... where stdev=standard deviation. The result can be seen in the lower left panel, blue curves are just there for reference: http://i48.tinypic.com/20shidd.png Am I doing something wrong here? Title: Re: Stats question (re: Fisher Transforms and Spatial Smoothing) Post by: bb113 on July 19, 2012, 06:19:51 PM Well I'm gunna go ahead and do it. If anyone questions it I'll just say it got the bitcoin forum stamp of silent approval.
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