I'am reading a book on DNA microarray data analysis and I'm trying to follow it analyzing a dataset of mine.
So until now I created boxplots, MAplots and correlation maps (using spearman's and concordance correlation coefficient methods) before and after the normalization (I used quantile normalization)
Now i would like to find out the outliers (some of them are shown in boxplots) and the book I'm reading suggests the resistant z-score
And we can call that value (X_gi) outlier if the z_gi is greater than 5 for example. Is such approach acceptable ? What do you think and what are you using in such cases ?
Any other idea on how to proceed on that step is welcomed.