FT_STATISTICS_MONTECARLO
Note that this reference documentation is identical to the help that is displayed in MATLAB when you type “help ft_statistics_montecarlo”.
FT_STATISTICS_MONTECARLO performs a nonparametric statistical test by calculating Monte-Carlo estimates of the significance probabilities and/or critical values from the permutation distribution. This function should not be called directly, instead you should call the function that is associated with the type of data on which you want to perform the test. Use as stat = ft_timelockstatistics(cfg, data1, data2, data3, ...) stat = ft_freqstatistics (cfg, data1, data2, data3, ...) stat = ft_sourcestatistics (cfg, data1, data2, data3, ...) Where the data is obtained from FT_TIMELOCKANALYSIS, FT_FREQANALYSIS or FT_SOURCEANALYSIS respectively, or from FT_TIMELOCKGRANDAVERAGE, FT_FREQGRANDAVERAGE or FT_SOURCEGRANDAVERAGE respectively and with cfg.method = 'montecarlo' The configuration options that can be specified are: cfg.numrandomization = number of randomizations, can be 'all' cfg.correctm = string, apply multiple-comparison correction, 'no', 'max', cluster', 'bonferroni', 'holm', 'hochberg', 'fdr' (default = 'no') cfg.alpha = number, critical value for rejecting the null-hypothesis per tail (default = 0.05) cfg.tail = number, -1, 1 or 0 (default = 0) cfg.correcttail = string, correct p-values or alpha-values when doing a two-sided test, 'alpha','prob' or 'no' (default = 'no') cfg.ivar = number or list with indices, independent variable(s) cfg.uvar = number or list with indices, unit variable(s) cfg.wvar = number or list with indices, within-cell variable(s) cfg.cvar = number or list with indices, control variable(s) cfg.feedback = string, 'gui', 'text', 'textbar' or 'no' (default = 'text') cfg.randomseed = string, 'yes', 'no' or a number (default = 'yes') If you use a cluster-based statistic, you can specify the following options that determine how the single-sample or single-voxel statistics will be thresholded and combined into one statistical value per cluster. cfg.clusterstatistic = how to combine the single samples that belong to a cluster, 'maxsum', 'maxsize', 'wcm' (default = 'maxsum') option 'wcm' refers to 'weighted cluster mass', a statistic that combines cluster size and intensity; see Hayasaka & Nichols (2004) NeuroImage for details cfg.clusterthreshold = method for single-sample threshold, 'parametric', 'nonparametric_individual', 'nonparametric_common' (default = 'parametric') cfg.clusteralpha = for either parametric or nonparametric thresholding per tail (default = 0.05) cfg.clustercritval = for parametric thresholding (default is determined by the statfun) cfg.clustertail = -1, 1 or 0 (default = 0) To include the channel dimension for clustering, you should specify cfg.neighbours = neighbourhood structure, see FT_PREPARE_NEIGHBOURS If you specify an empty neighbourhood structure, clustering will only be done over frequency and/or time and not over neighbouring channels. The statistic that is computed for each sample in each random reshuffling of the data is specified as cfg.statistic = 'indepsamplesT' independent samples T-statistic, 'indepsamplesF' independent samples F-statistic, 'indepsamplesregrT' independent samples regression coefficient T-statistic, 'indepsamplesZcoh' independent samples Z-statistic for coherence, 'depsamplesT' dependent samples T-statistic, 'depsamplesFmultivariate' dependent samples F-statistic MANOVA, 'depsamplesregrT' dependent samples regression coefficient T-statistic, 'actvsblT' activation versus baseline T-statistic. or you can specify your own low-level statistical function. You can also use a custom statistic of your choise that is sensitive to the expected effect in the data. You can implement the statistic in a "statfun" that will be called for each randomization. The requirements on a custom statistical function is that the function is called statfun_xxx, and that the function returns a structure with a "stat" field containing the single sample statistical values. Check the private functions statfun_xxx (e.g. with xxx=tstat) for the correct format of the input and output. See also FT_TIMELOCKSTATISTICS, FT_FREQSTATISTICS, FT_SOURCESTATISTICS