Question: challenging design matrix
gravatar for bpshiel
2.9 years ago by
bpshiel0 wrote:

Hi all,

Im using limma for differential expression.

I've been struggling with the concept of my experimental design analysis for a few days so i need some help.


My groups are something like this...

Feed condition survival
feed1 wet 10
feed1 wet 4
feed1 wet 6
feed1 wet 4
feed1 dry 3
feed1 dry 3
feed1 dry 4
feed1 dry 5
feed2 wet 10
feed2 wet 8
feed2 wet 5
feed2 wet 7
feed2 dry 9
feed2 dry 5
feed2 dry 6
feed2 dry 8
feed1+ dry 9
feed1+ dry 5
feed1+ dry 8
feed1+ dry 7

For example, this study is aimed at determining the genes that are responsible for higher Survival rates in dry environments when fed feed2 and feed1+ in comparison to  feed1, using a few different comparison between these 5 treatments.

the easiest method to do this i thought would be to just assign the 5 treatments to a group and then compare the comparisons im interested in.


Feed1wet, feed1dry, feed2wet, feed2dry and feed1+dry

My real issue, is that i have been struggling with wether to take Survival into account as a continuous variable.

I thought this made sense at first, but now considering my project aim of determining the genes that may be responsible for survival. I think that i will be masking the DE genes I'm interest in.

e.g. if i want to compare DE genes between feed1dry and feed1+dry to understand why feed1+ has higher survival in dry conditions, accounting for suvival as a continuous variable will mask what im interested in won't it?

what do you think?



ADD COMMENTlink modified 2.9 years ago by Gordon Smyth37k • written 2.9 years ago by bpshiel0
Answer: challenging design matrix
gravatar for Gordon Smyth
2.9 years ago by
Gordon Smyth37k
Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia
Gordon Smyth37k wrote:

Yes it would.

You could correlate genes directly with survival, but better to do that as a separate analysis without Feed and Condition.

ADD COMMENTlink modified 2.9 years ago • written 2.9 years ago by Gordon Smyth37k
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