rftPval: RFT p-values
In Tokazama/iClass: More intuitive syntax for manipulating imaging data

Description Usage Arguments Details Value Author(s) References See Also Examples

Calculates p-values of a statistical field using random field theory

1	rftPval(D, c, k, u, n, resels, df = c(idf, rdf), fieldType)

`D`	Image dimensions.
`c`	Number of clusters.
`k`	Spatial extent in resels
`u`	Statistical threshold.
`n`	Number of statistical field in conjunction.
`resels`	Resel measurements of the search region.
`df`	Degrees of freedom expressed as c(degrees of interest, degrees of error).
`fieldType:`	"T"T-field "F"F-field "X"Chi-square field" "Z"Gaussian field

This function calculates p-values of a thresholded statistical field at various levels:

set-level rft.pval(D, c, k, u, n, resels, df, fieldType)

cluster-level rft.pval(D, 1, k, u, n, resels, df, fieldType)

peak-level rft.pval(D, 1, 0, u, n, resels, df, fieldType)

Where set-level refers to obtaining the set of clusters, cluster-level refers to a specific cluster, and peak-level refers to the maximum (or peak) of a single cluster.

The probability of obtaining the specified cluster

"Pcor""corrected p-value" "Pu""uncorrected p-value" "Ec""expected number of clusters" "ek""expected number of resels per cluster"

Zachary P. Christensen

Friston K.J., (1994) Assessing the Significance of Focal Activations Using Their Spatial Extent. Friston K.J., (1996) Detecting Activations in PET and fMRI: Levels of Inference and Power. Worlsey K.J., (1996) A Unified Statistical Approach for Determining Significant Signals in Images of Cerebral Activation.

rftResults, resels

# generate some data as if we just fitted a linear regression
outimg1 <- makeImage(c(10, 10, 10), rt(1000))
maskimg <- getMask(outimg1)

# create clusters using arbitrary threshold
clusters <- image2ClusterImages(outimg1, minClusterSize=1, minThresh = 2, maxThresh = Inf)
fwhm <- estSmooth(outimg1, maskimg)
resels <- resels(mask, fwhm$fwhm)
peak <- max(clusters[[1]])
peakP <- rftPval(3, 1, 0, 2, 1, resels, c(1, 1), fieldType="T")