RATIO TRANSFORMATION OF RTCA DATA

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Description

Performs ratio transformation (normalisation) of RTCA data, as recommended by the producer Roche.

Usage

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Arguments

object

An object of RTCA

time

numeric, the time point used to normalize the whole series of data

Details

The xCelligence software provided by Roche performs ratio transform implicitly by dividing the time-series impedance measurement by the value of a selected time point (so-called 'base-time'), for instance 5 hours after compound transfection, in each cell. The aim of this transformation was to scale (normalize) the data of different wells, since the normalized values of all wells are uniformly 1 at the base-time.

However, this method is vulnerable to arbitrary selection of the time point chosen to normalize. It may be helpful to try several base-time values before comparing normalized results.

See derivativeTransform and rgrTransform for other normalization (scaling) possibilities.

Value

An object of RTCA, populated with normalized value. The normalized values of all wells are uniformly 1 at the base-time.

Author(s)

Jitao David Zhang jitao_david.zhang@roche.com

See Also

smoothTransform and interpolationTransform for smoothing and interpolating the RTCA data. rgrTransform calculates relative growth rate, derivativeTransform calculates derivatitve. The later two methods are not sensative to the selection of base-time point.

Examples

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require(RTCA)
  
ofile <- system.file("/extdata/testOutput.csv", package="RTCA")
x <- parseRTCA(ofile)

xNorm <- ratioTransform(x, 35)