edgeR: deDGE Fisher exact p-values
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Daniel Brewer ★ 1.9k
@daniel-brewer-1791
Last seen 10.2 years ago
It use to be that when you run deDGE from the edgeR library that it calculated the Fisher exact p-values and put it in a slot "exact". This no longer seems to be the case, with the p-values only being calculated when topTags() is called. This means that the plot example in the vignette no longer works i.e. > adj.p <- p.adjust(ms$exact, "fdr") > k <- (adj.p < 0.05) > plotMA(ms, col = c("black", "blue")[k + 1]) Have I missed something? How do you get round this? Thanks Dan -- ************************************************************** Daniel Brewer, Ph.D. Institute of Cancer Research Molecular Carcinogenesis Email: daniel.brewer at icr.ac.uk ************************************************************** The Institute of Cancer Research: Royal Cancer Hospital, a charitable Company Limited by Guarantee, Registered in England under Company No. 534147 with its Registered Office at 123 Old Brompton Road, London SW7 3RP. This e-mail message is confidential and for use by the a...{{dropped:2}}
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Mark Robinson ★ 1.1k
@mark-robinson-2171
Last seen 10.2 years ago
Hi Daniel. Thanks for the note. Indeed, there was a change in the package there as to where the exact p-values get calculated. I have mixed feeling on this, but the decision to move this to topTags() was based on the fact that we now support multiple groups yet the exact test is only realistic for 2-group comparisons. In topTags(), you must specify the pairwise difference of interest. I would welcome your feedback on this design decision as like I said, I have mixed feelings of how this should be done. The alternative is to precompute all the pairwise exact tests in deDGE() and maintain the $exact element. As to the vignette example, I suspect you are using an older vignette. The vignette for 1.2.x illustrates the same example with updated code. Hope that helps. Mark On 12-Aug-09, at 8:57 PM, Daniel Brewer wrote: > It use to be that when you run deDGE from the edgeR library that it > calculated the Fisher exact p-values and put it in a slot "exact". > This > no longer seems to be the case, with the p-values only being > calculated > when topTags() is called. This means that the plot example in the > vignette no longer works i.e. > >> adj.p <- p.adjust(ms$exact, "fdr") >> k <- (adj.p < 0.05) >> plotMA(ms, col = c("black", "blue")[k + 1]) > > Have I missed something? How do you get round this? > > Thanks > > Dan > > -- > ************************************************************** > Daniel Brewer, Ph.D. > > Institute of Cancer Research > Molecular Carcinogenesis > Email: daniel.brewer at icr.ac.uk > ************************************************************** > > The Institute of Cancer Research: Royal Cancer Hospital, a > charitable Company Limited by Guarantee, Registered in England under > Company No. 534147 with its Registered Office at 123 Old Brompton > Road, London SW7 3RP. > > This e-mail message is confidential and for use by the...{{dropped:23}}
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Hi Mark, Yes you are right I was using an old version of the vignette ... sorry about that. As for the design decision I have two suggestions: 1) A new function that simplifies exactTestNB (or modify exactTestNB itself) so that you only have to provide an EBList-class object and the groups (if more than two) and it returns a vector of results from the exact test 2) If there is two groups provide an $exact element from deDGE, but if not don't. Thanks Dan Mark Robinson wrote: > Hi Daniel. > > Thanks for the note. Indeed, there was a change in the package there as > to where the exact p-values get calculated. I have mixed feeling on > this, but the decision to move this to topTags() was based on the fact > that we now support multiple groups yet the exact test is only realistic > for 2-group comparisons. In topTags(), you must specify the pairwise > difference of interest. I would welcome your feedback on this design > decision as like I said, I have mixed feelings of how this should be > done. The alternative is to precompute all the pairwise exact tests in > deDGE() and maintain the $exact element. > > As to the vignette example, I suspect you are using an older vignette. > The vignette for 1.2.x illustrates the same example with updated code. > > Hope that helps. > Mark > > > On 12-Aug-09, at 8:57 PM, Daniel Brewer wrote: > >> It use to be that when you run deDGE from the edgeR library that it >> calculated the Fisher exact p-values and put it in a slot "exact". This >> no longer seems to be the case, with the p-values only being calculated >> when topTags() is called. This means that the plot example in the >> vignette no longer works i.e. >> >>> adj.p <- p.adjust(ms$exact, "fdr") >>> k <- (adj.p < 0.05) >>> plotMA(ms, col = c("black", "blue")[k + 1]) >> >> Have I missed something? How do you get round this? >> >> Thanks >> >> Dan >> -- ************************************************************** Daniel Brewer, Ph.D. Institute of Cancer Research Molecular Carcinogenesis Email: daniel.brewer at icr.ac.uk ************************************************************** The Institute of Cancer Research: Royal Cancer Hospital, a charitable Company Limited by Guarantee, Registered in England under Company No. 534147 with its Registered Office at 123 Old Brompton Road, London SW7 3RP. This e-mail message is confidential and for use by the a...{{dropped:2}}
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