Question: Skewness in RNA-Seq insert size

1

ashwini •

**100**wrote:Hi,

I aligned Illumina fastq reads (2x100bp) to **transcriptome using Bowtie2** and found that the mean insert size is ~180bp and SD ~60bp. By plotting the insert sizes I found that the data is right skewed and the skewness is ~1.69 which was obtained using "**skewness**" from the package "**e1071**".

I tried to obtain this type of data from "**rsnorm**" where we can specify skewness parameter.

rsnorm(3000000, mean = 180, sd = 60, xi = 1.69)

Xi is the skewness parameter.

But the plot I get is more symmetrical and also skewness is **0.69** while the mean and SD remain the same (180bp and 60bp respectively).

I tried with different values for Xi and I always end up with values -1 to 1. So I am confused here.

It will be helpful to know where I am going wrong.

Thanks in advance.

Hello ashwini!

It appears that your post has been cross-posted to another site: SEQanswers.

This is typically not recommended as it runs the risk of annoying people in both communities.

97kI am sorry! I thought I will get answer from either of them.

100