fmri.cluster: Cluster thresholding.
In neuroconductor-devel-releases/fmri: Analysis of fMRI Experiments

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

Detection of activated regions using cluster thresholding.

1	fmri.cluster(spm, alpha = 0.05, ncmin = 2, minimum.signal = 0)

`spm`	`fmrispm` object
`alpha`	multiple test (over volume and cluster sizes) adjusted significance level used for thresholds.
`ncmin`	minimal cluster size used. An activation is detected if for any clustersize in `nvmin:20` the size specific threshold is exceeded.
`minimum.signal`	allows to specify a (positive) minimum value for detected signals. If minimum.signal >0 the thresholds are to conservative, this case needs further improvements.

Approximate thresholds for the existence of a cluster with mean t-statistics exceeding a 1-beta threshold k_{nc} for cluster size nc are based on a simulation study under the hypothesis and adjusted for both degrees of freedom, number of voxel in mask and spatial correlation. beta is choosen such that under the hypothesis the combined (over cluster sizes ncmin:20) test has approximate significance level alpha.

Object with class attributes "fmripvalue" and "fmridata"

`pvalue`	p-values of voxelwise t-statistics for voxel that were detected for any cluster size, a value of `1` otherwise.
`weights`	voxelsize ratio
`dim`	data dimension
`hrf`	expected BOLD response for contrast (single stimulus only)