[Genome] Table browser / FTP site discrepancy

[Benjamin Berman]

I am trying to use the regulatory potential 7 species track for some  
analysis.  I am using hg17.  I first downloaded some regions using  
the table browser.  For chrom 19, position 52426843, I get a value of  
0.0458949 (see the table browser output .txt file attached to this  
email):

teaview2:~/genome_data/build35_7x_reg_pot.subsets benb$ grep 52426843  
build35_7x_reg_pot_vega_nonbinding.txt
52426843        0.0458949

But when i download the entire chromosome wiggle track from the FTP  
server (ftp://hgdownload.cse.ucsc.edu/goldenPath/hg17/regPotential7X/ 
chr19.regPotential7X.hg17.gz), I get a different score of 0.049367:

teaview2:~/genome_data/build35_7x_reg_pot.subsets benb$ grep  
52426843 ../build35_7x_reg_pot/chr19.regPotential7X.hg17
52426843 0.049367

Is this because of the compression alluded to in the table browser  
output?  It says that worst case loss in resolution is 1.7e-05, but  
this is a difference of more than 1e-3.  Do you know why these two  
don't match up more closely?

Thanks for your help,
Ben Berman


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