Hi there,
I am using the tool RNASeqReadSimulator (http://alumni.cs.ucr.edu/~liw/rnaseqreadsimulator.html), in order to simulate RNA-seq reads. In the fist script (there are 3), it is possible to specify expression values to the genes.
python genexplvprofile.py -h -e/--lognormal mu,sigma Specify the mean and variance of the lognormal distribution used to assign expression levels. Default -4,4
I'm not very good at statistics and I would like to know, which parameters of mu and sigma should be OK if I want to have all the genes expressed in my simulated data.
Any idea or suggestion..?
Thanks
1 answer
Since it says there that the distribution of gene expression level will be generated on a lognormal distribution the best way to evaluate these parameters is to look at the shape of the curve for various parameters:
http://en.wikipedia.org/wiki/Log-normal_distribution
In those plots imagine that the horizontal axis corresponds to the gene expression levels whereas the vertical axis corresponds to the fraction of genes that express at a given level. You can use an online calculator to display what the distributions would look like
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When in doubt the defaults are a good start
Yes, sure. But I was thinking that if I put a HIGH mean value and LOW variance, maybe can I simulate to have all the genes expressed? But I don't know which number is "high" or "low".. and maybe it depends on the number of genes...