mkda
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mkda [2011/12/08 22:47] – updated jochen | mkda [2012/02/28 16:08] – added description of algorithm jochen | ||
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For the actual procedure of running the MKDA, please refer to the [[neuroelf_gui - MKDA UI|MKDA UI]] article. | For the actual procedure of running the MKDA, please refer to the [[neuroelf_gui - MKDA UI|MKDA UI]] article. | ||
+ | ===== Algorithm description ===== | ||
+ | The general algorithm works as follows: | ||
+ | |||
+ | * potentially, | ||
+ | * for each study or contrast (whatever is used as statistical unit) included in a given analysis a weight is computed (i.e. normally this weight is equal across peaks within a study/ | ||
+ | * next, a voxel based volume is initialized (filled with zeros) for each of the statistical units, and for each point in any given study a blob (with configurable size and value distribution, | ||
+ | * eventually, these volumes are combined using the weights for each of the statistical units (weighted sum) | ||
+ | * to draw inferences, an empirical null distribution is derived by either spatially scrambling coordinates within a reasonable mask, such as a grey matter volume in the same space (in which case the null hypothesis tests whether the observed summary statistic of the weighted sum of blobs in any given location is higher than warranted by chance for that particular location) or by scrambling the labels of peaks (i.e. in a differential contrast where two sets of peaks reported for different activation states/ | ||
+ | * to allow fMRI-typical inference (uncorrected thresholding, |
mkda.txt · Last modified: 2012/02/28 16:17 by jochen