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Ancova analysis on two linear regressions (from microscopy data)

Posted 11 years ago
 Hello everybody,I would like to kindly ask for your help.the results of the microscopy analysis I perform on a specific specimen are two images taken with different wavelengths (405 and 488). It is possible to plot the intensities of a specific pixel at 405,x and 488,y (in a scatter plot for example) and to fit a linear regression line.Changes in the regression slopes are observed depending on the treatments performed to the specimen, between condition A and B. I would like to determine if two regressions are statiscally significant. I believe I need to perform an ANCOVA for that. However, I still wasn't able to compute it in mathematica specially because I have problems describing the nominal variable.Could you please give me some tips?Thank you very much for your time,AnaThis is my procedure so far:1. Loading 4 images: A405, A488, B405, B4882.PixA405 = Flatten[ImageData[A405, "Bit16"]];PixA488 = Flatten[ImageData[A488, "Bit16"]];PixB405 = Flatten[ImageData[B405, "Bit16"]];PixB488 = Flatten[ImageData[B488, "Bit16"]];3.TabA405A488 = Table[{PixA405[], PixA488[]}, {n, 1, PixNo}];TabB405B488 = Table[{PixB405[], PixB488[]}, {n, 1, PixNo}];4.LinearFit1 = LinearModelFit[TabA405A488, {x}, x]LinearFit2 = LinearModelFit[TabB405B488, {x}, x]
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Posted 11 years ago
 I am not super strong in statistic and I am not sure if I understood your problem correctly.However you don't need LinearModelFit to fit a line between two points,sA = (Flatten[ImageData[A488, "Bit16"]] - Flatten[ImageData[A405, "Bit16"]])/(488-405)andsB = (Flatten[ImageData[B488, "Bit16"]] - Flatten[ImageData[B405, "Bit16"]])/(488-405)already contain all the slopes.What kind of relation do you expect between sA and sB (namely the effect of the treatments)?
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