• Create Account

Submit your paper to J Biol Methods today!

# In 2^ minus ddCt method, why is the "minus" sign?

qPCR Data Analysis Relative Quantitation 2^ddCt Method

### #1 Serratia

Serratia

member

• Members
• 1 posts
0
Neutral

Posted 24 January 2014 - 06:12 AM

For the qPCR relative quantitation, we use the 2^-ddCt method. I was wondering why the minus sign before ddCt?

### #2 Tabaluga

Tabaluga

Making glass out of shards

• Active Members
• 432 posts
54
Excellent

Posted 24 January 2014 - 12:32 PM

If I understood it correctly, ddCt is dCt(sample) - dCt(reference), -ddCt would be -(dCt(sample) - dCt(reference)), which equals dCt(reference) - dCt(sample), so it's just another way of calculating.

But I have also seen ddCt referred to as dCt(reference) - dCt(sample), then it would be the other way round...

Il dort. Quoique le sort fût pour lui bien étrange,
Il vivait. Il mourut quand il n'eut plus son ange;
La chose simplement d'elle-même arriva,
Comme la nuit se fait lorsque le jour s'en va.