cluster-based analysis

Emanuel van den Broeke e.vandenbroeke at ANES.UMCN.NL
Wed Sep 29 10:43:00 CEST 2010

Dear Michael and others,
I am thinking about an alternative cluster based statistic, but do not know if 
this is also valid.

The alternative method goes as follows:
1.	Calculate t-statistics of two conditions only on the observed data.
2.	Determine cluster(s) based on a threshold (critical t-value).
3.	Calculate the sum of the cluster(s).
4.	Take the cluster with the highest absolute value (Sum-score) if more 
than 1 clusters are present.
5.	Calculate the mean ERP activity, based on the highest cluster, in the 
individual trials.
6.	Use a non-parametric (Wilcoxon, Mann-Withney U, dependent of the 
type of experiment) test statistic to test whether there is a difference (two 
sided) between the two group means for this highest cluster.

Do you or anybody else think this is also a valid method for identifying and 
testing relevant ERP activity?


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