Question: Definition of the CellHTS2 normalizePlates parameter scale

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c.lieftink@nki.nl •

**20**wrote:Hello everyone,
The cellHTS2 method normalizePlates has a parameter called "scale".
The two values are "additive" vs. "multiplicative". Although it seems
be some basic statistical knowledge I am not able to find a clear
definition of additive versus multiplicative data scale. Can anyone
provide me with one? I have searched the internet but could not find
one.
2) In cellHTS2 the scale value has the following influence on
normalizing with "median":
additive: the measurement is divided by the median
multiplicative: the median is subtracted from the measurement
I assume that a cellcount is additive data. It is my understanding
that the most used method for normalization in RNAi screens is
dividing by the median. However, cellHTS2 does not offer that option
for additive data. Would it a good idea when the end user is offered
to possibility to choose for his/her (additive) data to subtract or
divide by the median?
3. I am working with cellHTS2 2.2.5. Maybe something has changed in
2.4.1, but I was not able to find any release notes.
Best regards,
Cor

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modified 11.0 years ago
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Elin Axelsson •

**60**• written 11.0 years ago by c.lieftink@nki.nl •**20**