Thanks.. so instead of looking at Boxplot, I have to do PCA analysis of my data, to remove an outlier.
Hi everyone, I have downloaded the RNA_seq data for PAAD cancer type using TCGA assembler. TCGA assembler also generates a boxplot image, showing outliers. PAAD boxplot for RNA seq data
So my question is this- 1. Is, I have to remove these Outliers sample from my study, as I have to do Differential gene expression analysis. Thanks in advance.
1 answer
Outliers are best assessed from PCA, not from boxplots.
Yeah do PCA on all the expressed genes and then on the most variable ones with a few thresholds using co efficient of variation or something similar.
Keep in mind that there is no standard way to statistically define an outlier. If you want, come back here to post your PCA bi-pĺot that you obtain.
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Which outlier samples? - the data distributions across this large number of samples look quite similar. A box-and-whisker plot is only part of the story, of course. You should additionally look at a PCA bi-plot of PC1 versus PC2.
Alternatively, if you are using limma or edgeR you can use their robust setting when fitting the linear models so that outlier samples will have less influence on your results.