Hello, I am trying to normalize my data from titration controls with the composite method. First of all I would like to know why this method is not recommended any more by the author (in a previous mail from Gordon Smyth). Otherwise here is my problem if it is of any interest to go on with this method : the function returns an error that has already been mentioned in the mailing list but it seems to me that I don't have a problem with my controlspots variable. Here is the command line I am using : nMA <- gif.normalizeWithinArrays(MA, layout=MA$printer, method="composite", controlspots=ctrlspots) where ctrlspots : str(ctrlspots) logi [1:864] TRUE FALSE FALSE FALSE FALSE FALSE FALSE FALSE TRUE TRUE FALSE FALSE ... and MA$M : str(MA$M) num [1:864, 1:6] -0.2679 -0.1382 1.3026 0.0359 -0.9560 ... The error returned is : Number of Observations: 192 Equivalent Number of Parameters: 4.95 Residual Scale Estimate: 0.12 Error in predLoess(object$y, object$x, newx, object$s, object$weights, : NA/NaN/Inf in foreign function call (arg 3) This error comes from the predict function : predict(fit, newdata=x) There are infinite values in x in my data and in the function there no treatment with. Thanks a lot, Laetitia.