Question: interpreting FIMO results - p value and q value
0
gravatar for Affan
4.2 years ago by
Affan290
Canada
Affan290 wrote:

I used FIMO to scan promoter regions (defined as 10,000 upstream from TSS) only on chromosome 1 of mm9. The results can be viewed here: http://nbcr-222.ucsd.edu/opal-jobs/appFIMO_4.10.01429210665330517302090/fimo.html

I have a couple of questions:

1) For each gene ('sequence name'), it finds a hit on both the positive and negative strand. What does this mean? Can I get rid of one of them and only consider the positive strand? Even the start and end coordinates are the same.

2) Could someone explain to me the p value (and the corresponding q value)? Since the results are sorted by p value and the first result has a p value of 1.64e-6 .. doesn't that mean that that hit is deemed to be a true positive? Why then is the q value so high? Why are my q values so high regardless?

3) I have a control data set. Its a chip seq experiment on the transcription factor of interest. Can I just go through the results from FIMO and determine which results lie within the peaks of the chipseq experiment and as that information to create sensitivity analysis?

motif position weight matrix • 2.0k views
ADD COMMENTlink modified 4.2 years ago • written 4.2 years ago by Affan290
1
gravatar for RamRS
4.2 years ago by
RamRS21k
Houston, TX
RamRS21k wrote:

1) If the motif you're looking for is its own reverse complement, you'll definitely find hits on both strands between the same co-ordinates.

EDIT: Just checked your motif (CTATATATAG - this is its own reverse complement, so your results are expected)

2) Not sure about this. Maybe the q-value is low only for really long or really specific/rigid motifs. Maybe your motif matrix is a bit lenient.

3) You could definitely do that. Correlating an analysis of the p-values would also give you a weighted measure of sensitivity.

ADD COMMENTlink modified 4.2 years ago • written 4.2 years ago by RamRS21k
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