Question: cross platform microarray normalization
0
gravatar for nazaninhoseinkhan
3.3 years ago by
Iran, Islamic Republic Of
nazaninhoseinkhan360 wrote:

Dear all,

I am trying to perform cross platform normalization between affymetrix, illumina and agilent microarray data.

I know I can do it using Combat package which is now available in SVA package in R.

My problem is I have not recognized yet the structure of input files in SVA. The manual works with bladderbatch and phenodata that their structures is not clear.

I will appreciate any advice 

Nazanin

combat sva R • 1.7k views
ADD COMMENTlink modified 3.3 years ago by andrew.j.skelton735.7k • written 3.3 years ago by nazaninhoseinkhan360
0
gravatar for andrew.j.skelton73
3.3 years ago by
London
andrew.j.skelton735.7k wrote:

Not an easy task by any means. You'll need experiments where your sample types of interest are the same, i.e. control and wt must be the same. You'll then need to normalise each experiment, and convert identifiers to a common type, such as nuID. nuID is the most reliable as it ensures that you're using the same capture sequences. Take each of your normalised matrices, and column bind them, same with the phenotype data. To find differential expression, you include your "batch effect", or cross experiment effect in your linear model design. I'd advise against combat, there was a paper released recently to show it inflated the effects that you wanted to see (paper here)

You have to remember that this is a very difficult task, and there are a lot of technical effects you're trying to overcome. Consider a non-parametric approach to this problem too, it may act as a validation of sorts. Perform each differential expression test in each experiment, then look for common differentially expressed genes across experiments. 

ADD COMMENTlink modified 3.3 years ago • written 3.3 years ago by andrew.j.skelton735.7k
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