why should we filter cell which has low percent of ribosomal reads？

[gudeqing]

hi, here are two filtering steps of this tutorial:

selected_mito <- WhichCells(data.filt, expression = percent_mito < 0.2)
selected_ribo <- WhichCells(data.filt, expression = percent_ribo > 0.05)

would you please explain more about why we should filter cell which has low percent of ribosomal reads？

[dmj6288]

I'd also like to add that percent_mito < 0.2 does not filter cells with less than 20 % MT expression. It filters cells less than 0.2 % MT expression. This is only when you use method 1 of calculating MT percent, because it returns the percentage rather than the fraction as is implied here.