I am using deeptools to make bigwig files for 4 similar group of CHIPseq data. question1: my bigwig data are very different from each other, size difference some are around 259Mb but others are around 50Mb in size. What could cause this differences as my sample were treated the same and used the same way to sequence. I used RPKM to normalize. question2: when I am doing computeMatrix and plotHeatmap. The output of the plotprofile showing different basal levels. Is there a way to adjust the basel level or normalize it? Since I have already used RPKM to normalize the bigwig file, is there other normalization needed for this?