We used poly-A bulk RNA sequencing and single-cell RNA sequencing using mixtures of well-characterized purified cell lines to better understand measurement noise between technologies. A375, HAP1, THP1, HEK239FT, K562, and A549 cells were mixed in various proportions to generate four in vivo cell mixtures that mimic tissues. Mixtures of 6, 4, 2, and 1 of the cell types are respectively denoted 6ct, 4ct, 2ct, and 1ct. In the included zip, directories are labeled using this notation, followed by a list of cell types in the mixture after an underscore. In each directory, bulk and single cell count data is included.