How to find out off target reads?

Question

[gskbioinfo143]

Here is the summary of Ion Torrent run result. Valid reads is only 19% how to improve it? How to find reads outside target region?

Reads                   21481392
Mapped Reads            19442218
Mapped %                90.50725391
Valid Reads             19.67%
Total-Reads on Target   3823517
On Target               24.72%
Off Target Reads        15618701

[Pierre Lindenbaum]

Can't resist citing @BioMickWatson ...

@yokofakun I find "rm *.fastq" works best for Ion Torrent data

— Mick W@tson 🐄 (@BioMickWatson) June 29, 2015

[gskbioinfo143]

what the meaning of ur message?

[Brian Bushnell]

Oh, come on... I agree for Solid, but surely Ion Torrent is much better.