Relative expression between controls and subjects

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Relative expression between controls and subjects

Postby rima250 » Dec 03 2017 4:38 pm

Dear experts,
As far as I know, the relative expression difference between controls and subjects comes from difference between controls and subjects. In a way, that controls would assign as 0 or 1 and subjects' results varies by over or lower expression compared to fixed control results.I have noticed in some articles which neither of the groups have fixed number. How possible to have e.g. 0.2 or 1.3 fold changes for controls?
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Re: Relative expression between controls and subjects

Postby relaxin » Dec 04 2017 2:05 am

The fold change is defined as the expression level of experimental/expression level of control. Then the control is set at "1". A 1.3 fold change will be slight increase over control. A 0.2 fold change will be a decrease down to 20% of control.

The control value should not be set to "0", as you cannot divide any number by "0".
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Re: Relative expression between controls and subjects

Postby rima250 » Dec 08 2017 7:52 am

My question is: how could the expression for controls less than 1? As we compare subjects to controls, and expression for controls could not be e.g. 0.2.
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Re: Relative expression between controls and subjects

Postby relaxin » Dec 13 2017 5:05 pm

The control is always set to "1". The experimental is expressed as fold over control. A value of "0.2" is 1/5 of control, while a value of "2" is 2-fold over control. You may read the details of calculation in the link below:

https://bitesizebio.com/29322/methods-r ... qpcr-data/
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