Implications of design argument to limma::voom?
1
1
Entering edit mode
@ryan-c-thompson-5618
Last seen 8 months ago
Scripps Research, La Jolla, CA
Hi, I'm using limma's voom function to analyze some of my data, and I'm wondering about the implications of the design argument to voom. The default design is an intercept-only design, i.e. a model formula of ~1. However, I can also pass in the same experimental design that I will pass to lmFit later (or conceivably any other design). I'm not entirely sure what assumptions I'm making by choosing either of these options. Can someone familiar with such things explain what the implications of passing or not passing a design to voom are? Similarly, I have the same question for DESeq's varianceStabilizingTransformation: I can use estimateDispersions with or without a design matrix and then do the VST either way, and I'm not sure what assumptions I am making in either case. Thanks, -Ryan Thompson
• 957 views
ADD COMMENT
1
Entering edit mode
@gordon-smyth
Last seen 8 hours ago
WEHI, Melbourne, Australia
Hi Ryan, The design matrix to voom must be the same as you use for lmFit (or be an alternative parametrization of the same model), otherwise voom is analysing the wrong variances. Best wishes Gordon ------------------ original message -------------------- [BioC] Implications of design argument to limma::voom? Ryan C. Thompson rct at thompsonclan.org Wed Jun 5 01:03:27 CEST 2013 Hi, I'm using limma's voom function to analyze some of my data, and I'm wondering about the implications of the design argument to voom. The default design is an intercept-only design, i.e. a model formula of ~1. However, I can also pass in the same experimental design that I will pass to lmFit later (or conceivably any other design). I'm not entirely sure what assumptions I'm making by choosing either of these options. Can someone familiar with such things explain what the implications of passing or not passing a design to voom are? Similarly, I have the same question for DESeq's varianceStabilizingTransformation: I can use estimateDispersions with or without a design matrix and then do the VST either way, and I'm not sure what assumptions I am making in either case. Thanks, -Ryan Thompson ______________________________________________________________________ The information in this email is confidential and intend...{{dropped:4}}
ADD COMMENT
0
Entering edit mode
Thanks. That answers my question. On Tue 04 Jun 2013 04:21:44 PM PDT, Gordon K Smyth wrote: > Hi Ryan, > > The design matrix to voom must be the same as you use for lmFit (or be > an alternative parametrization of the same model), otherwise voom is > analysing the wrong variances. > > Best wishes > Gordon > > ------------------ original message -------------------- > [BioC] Implications of design argument to limma::voom? > Ryan C. Thompson rct at thompsonclan.org > Wed Jun 5 01:03:27 CEST 2013 > > Hi, > > I'm using limma's voom function to analyze some of my data, and I'm > wondering about the implications of the design argument to voom. The > default design is an intercept-only design, i.e. a model formula of ~1. > However, I can also pass in the same experimental design that I will > pass to lmFit later (or conceivably any other design). I'm not entirely > sure what assumptions I'm making by choosing either of these options. > Can someone familiar with such things explain what the implications of > passing or not passing a design to voom are? > > Similarly, I have the same question for DESeq's > varianceStabilizingTransformation: I can use estimateDispersions with or > without a design matrix and then do the VST either way, and I'm not sure > what assumptions I am making in either case. > > Thanks, > > -Ryan Thompson > > ______________________________________________________________________ > The information in this email is confidential and inte...{{dropped:6}}
ADD REPLY

Login before adding your answer.

Traffic: 737 users visited in the last hour
Help About
FAQ
Access RSS
API
Stats

Use of this site constitutes acceptance of our User Agreement and Privacy Policy.

Powered by the version 2.3.6