Fig. 4

Comparison of all normalization methods on good quality data. We compare normalization factors on a high quality data set [23] (GSE96869) computed by four distinct methods: VSI applied to the internal 3\(^\prime\) invariant gene set (blue), VSI applied to an external Drosophila spike-in (red), the ratio approach applied to the 3\(^\prime\) invariant gene set (yellow), and the ratio approach applied to the Drosophilia spike-in (green). Error bars are shown for the VSI estimates. The 3\(^\prime\) invariant set uses a threshold of 180 kb (60 min), regardless of the data time point. For orientation, we note the normalization factor of zero (red dotted line), the onset of biological replication arrest and the assumed time point for the 3\(^\prime\) invariant gene set