Why product sizes differ so much among different single cell RNA sequencing datasets?

Question

[Snow Yeung]

Hi there,

Recently I want to download some scRNA-seq data from public database. During searching, I found that some scRNA-seq datasets may have around 2~3Gb for one sample (no matter PE or SE), but some just around 30Mb~300Mb. It's werid for me since I just familiared with bulk cells RNA sequencing and these runs usually have serveral Gb sizes per sample. Are the size around several Mb normally for one scRNA-seq sample data? And how to analyze these small size scRNA-seq datasets? Any help would be apperciate!

[h.mon]

Maybe the (simple and obvious) reason is just multiplexing more samples?

There are two other possible factors: there are huge variations in how much RNA particular cells have; and single cell RNA yields low amount of RNA, sequencing at great depth is only likely to increase duplication level.