> design = model.matrix(~ fac1 * fac2 * data_to_model$Time) > fit = lmFit(data_to_model, design) Error in rowMeans(y$exprs, na.rm = TRUE) : 'x' must be numeric > design = model.matrix(~ fac1 * fac2 * data_to_model$Time * data_to_model$Value) > fit = lmFit(data_to_model, design) Error in rowMeans(y$exprs, na.rm = TRUE) : 'x' must be numeric fac1 is a factor fac2 is a factor data_to_model$Time is a numeric my data_to_model data.frame is something like that Tissue Type Time Value Tis1 Ty1 Ti1 Val1 Tis1 Ty1 Ti1 Val2 ... and fac1 = factor(data_to_model$Type) fac1 = factor(data_to_model$Tissue) where is the midtake in R..any help plz [[alternative HTML version deleted]]