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Help to understand some terms

I'm new to the field of bioinformatics (and I'm not from the field of biology), and I don't understand some terms in gene expression analysis:
I read about RNA-seq that it's important to use some replicates. What is the meaning of replicates here? I know the process of dna replication, but it does not seem useful to use copies of the same DNA.
And what exactly is outlier in RNA-seq analysis? I read that the more replicates we have the easier it is to detect outliers. Can you explain it to me please?

Thanks.

gene-expression rna-seq
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updated by Lars Juhl Jensen Lars Juhl Jensen • written by yuvaltechnion • yuvaltechnion

1 answer

The words replicates and outliers are terms from statistics. Wikipedia gives a very good explanation of both:

Long story short, replicates means that you do the experiment more than once and outliers typically represent experimental errors. Obviously, if you repeat an experiment, it makes it a lot easier to identify erroneous measurements.

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written by Lars Juhl Jensen Lars Juhl Jensen

To add a simple example to this:
If you do 3 measurements and get values 5 9 and 6 you don't know if those values belong to the same distribution, or maybe that 9 is an outlier.
If you do 12 more measurements and get values 5 9 6 4 5 6 5 6 6 4 6 6 4 6 4 it does become clear that 9 could be an outlier.

Both for this artefact as for true biological variability: more replicates give you more power to make discoveries

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written by WouterDeCoster WouterDeCoster

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