Discrepancies in phyloP100way

[ohad g]

Hi Team,

I have a question regarding the title above.

I downloaded the chr.phyloP100way.wigFix files from your web site.

I see different numbers on the files when compared to the online Genome Browser.

For example:

But on the wigFix files (attached) I do not see those Maximum/Minimum/Mean values:

1) Maximum of 7.44343 on the web and 7.41 on the wigFix files

2) Minimum of -2.16785 on the web and -2.096 on the wigFix files

3) Average of 2.81571 on the web and 2.880029 on the wigFix files

Can you kindly advise on why I see this differences ?

Best,

--Ohad

[Matthew Speir]

Hello Ohad,

Thank you for your question about the 100-way PhyloP data in the UCSC Genome Browser. From the help page for the wiggle
format (which includes wigFix files):

    "For speed and efficiency, wiggle data is compressed and stored internally in 128 unique bins. This compression means
    that there is a minor loss of precision when data is exported from a wiggle track (i.e., with output format 'data points'
    or 'bed format' within the table browser)."

For more information on the wiggle format, see the help page: http://genome.ucsc.edu/goldenPath/help/wiggle.html.
The README file from the PhyloP directory, http://hgdownload.cse.ucsc.edu/goldenPath/hg19/phyloP100way/README.txt,
on our download server contains a lot of useful information about the files, the file formats and links to relevant help pages.

I hope this is helpful. If you have any further questions, please reply to gen...@soe.ucsc.edu. All messages sent to that
address are archived on a publicly-accessible Google Groups forum. If your question includes sensitive data, you may
send it instead to genom...@soe.ucsc.edu.

Matthew Speir
UCSC Genome Bioinformatics Group

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