[BioC] limma report logFC confidence interval?

Gordon K Smyth smyth at wehi.EDU.AU
Sat Oct 30 01:12:35 CEST 2010


Sunny's CI is exactly right.

CIs could be an option in topTable(), but this the first request for them, 
so the demand doesn't seem enough for now.

Best wishes
Gordon

> Date: Fri, 29 Oct 2010 00:14:39 -0400
> From: Sunny Srivastava <research.baba at gmail.com>
> To: Timothy Wu <2huggie at gmail.com>
> Cc: bioconductor <bioconductor at stat.math.ethz.ch>
> Subject: Re: [BioC] limma report logFC confidence interval?
>
> Hello Thomas,
> I am sure senior members of the list will have more to say, here is my
> $0.02.
>
> logFC is the coefficient of the treatment in your model. Assuming that you
> have a model with only one treatment
>
> log Int_g = b0 + b1 * trt
>
> b1 = logFC
>
> The CI of logFC can be found in the same manner as you would do in normal
> linear regression, but here instead of usual t(0.975, df) quantile, you
> should use the moderated t quantile ie t(0.975, df.residual + df.prior)
>
> So the 95% CI for logFC will be
>
> logFC -+ t(0.975, fit3$df.residual + fit3$df.prior) * fit3$stdev.unscaled *
> sqrt(fit3$s2.post)
>
>
> Please correct me if I am wrong.
>
>
> Thanks,
> S.
>
> On Thu, Oct 28, 2010 at 7:46 AM, Timothy Wu <2huggie at gmail.com> wrote:
>
>> HI,
>>
>> Is there a way to report the CI of logFC from topTable in limma? I googled
>> around and it doesn't seem easy to find. I was expecting the option to be
>> in
>> topTable().
>>
>> Thanks,
>>
>> Timothy

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