Question: Why shouldn't you ever compare TPM values across samples?
0
gravatar for razbarz
10 weeks ago by
razbarz • 0
razbarz • 0 wrote:

There is a warning in red letters in galaxy manual:

"You should NEVER EVER use RPKM, FPKM, or TPM to compare expression levels across samples. These are RELATIVE measures! Consider yourself warned!"

Why? If I want to compare gene X between samples, and TPM normalizes to total reads, shouldn't it be ok to say gene X increase between samples 1 and 2? If someone can direct me to a clear explanation that would be very appreciated

Thanks

tpm • 214 views
ADD COMMENT • link • modified 9 weeks ago by Jennifer Hillman Jackson ♦ 25k • written 10 weeks ago by razbarz • 0
0
gravatar for Jennifer Hillman Jackson
9 weeks ago by
United States
Jennifer Hillman Jackson ♦ 25k wrote:

Hello,

Using count data directly is more scientifically accurate. Comparing statistics based on a single sample won't result in useful comparison results between samples.

There is much discussion online about this, please review: https://www.google.com/search?q=TMP+differentail+expression+analysis&oq=TMP+differentail+expression+analysis&aqs=chrome..69i57.9540j0j7&sourceid=chrome&ie=UTF-8

Thanks! Jen, Galaxy team

ADD COMMENT • link written 9 weeks ago by Jennifer Hillman Jackson ♦ 25k
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