I'm interested in checking if some genes I have are tissue-specific in their expressions. I'm working with TPM normalized counts and want to use the Tau statistic to measure specificity. I think this article has the most comprehensive description of Tau. In the same article they work with RPKM normalized counts which then they log-transform before proceeding to Tau calculation. In my case I also log-transform TPMs, but also apply Quantile Normalization before carrying out some other downstream analyses. My question is if I need to go back to the expression matrix I had before Quantile Normalization or if it should be fine to calculate Tau even after Quantile Normalization.