Unit of the predicted values

[gpwhiz]

Hello,
I wanted to know the unit of the values in the predicted gene expression output file, as the value ranges from negative to positive. I have tried to look up this information in the original paper, but couldn't find it.
Are the values in log, or compared to some housekeeping gene, as the GTEx has TPM unit..
If I am missing something, please direct me to the right publication.

[hakyim]

the prediction models were trained on inverse normalized expression levels from GTEx, hence both positive and negative values will be generated. We use the same pre-processing as GTEx eQTL analysis.