normalize.qspline {affy} | R Documentation

## Normalize arrays

### Description

normalizes arrays in an AffyBatch each other or to a set of target intensities

### Usage

    normalize.AffyBatch.qspline(abatch,type=c("together", "pmonly", "mmonly",
                     "separate"), ...)

    normalize.qspline(x, target = NULL, samples = NULL,
                      fit.iters = 5, min.offset = 5,
                      spline.method = "natural", smooth = TRUE,
                      spar = 0, p.min = 0, p.max = 1.0,
                      incl.ends = TRUE, converge = FALSE,
                      verbose = TRUE, na.rm = FALSE)

### Arguments

`x` | a `data.matrix` of intensities
`abatch` | an `AffyBatch`
`target` | numerical vector of intensity values to normalize to. (could be the name for one of the celfiles in 'abatch')
`samples` | numerical, the number of quantiles to be used for spline. if (0,1], then it is a sampling rate
`fit.iters` | number of spline interpolations to average
`min.offset` | minimum span between quantiles (rank difference) for the different fit iterations
`spline.method` | specifies the type of spline to be used. Possible values are `"fmm"', `"natural"', and `"periodic"'.
`smooth` | logical, if `TRUE', smoothing splines are used on the quantiles
`spar` | smoothing parameter for `splinefun', typically in (0,1].
`p.min` | minimum percentile for the first quantile
`p.max` | maximum percentile for the last quantile
`incl.ends` | include the minimum and maximum values from the normalized and target arrays in the fit
`converge` | (currently unimplemented)
`verbose` | logical, if `TRUE' then normalization progress is reported
`na.rm` | logical, if `TRUE' then handle NA values (by ignoring them)
`type` | A string specifying how the normalization should be applied. See details for more.
`...` | Optional parameters to be passed through

### Details

This normalization method uses the quantiles from each array and the target to fit a system of cubic splines to normalize the data. The target should be the mean (geometric) or median of each probe but could also be the name of a particular chip in the `abatch` object.

Parameters setting can be of much importance when using this method. The parameter `fit.iter` is used as a starting point to find a more appropriate value. Unfortunately the algorithm used do not converge in some cases. If this happens, the `fit.iter` value is used and a warning is thrown. Use of different settings for the parameter `samples` was reported to give good results. More specifically, for about 200 data points use `samples = 0.33`, for about 2000 data points use `samples = 0.05`, for about 10000 data points use `samples = 0.02` (thanks to Paul Boutros).

The `type` argument should be one of `"separate","pmonly","mmonly","together"` which indicates whether to normalize only one probe type (PM,MM) or both together or separately.

### Value

a normalized `AffyBatch`.

### Author(s)

Laurent and Workman C.

### References

Christopher Workman, Lars Juhl Jensen, Hanne Jarmer, Randy Berka, Laurent Gautier, Henrik Bj{o}rn Nielsen, Hans-Henrik Saxild, Claus Nielsen, S{o}ren Brunak, and Steen Knudsen. A new non-linear normal- ization method for reducing variability in dna microarray experiments. Genome Biology, accepted, 2002

[Package affy version 1.8.1 Index]