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tutorial:shared:cluster_permutation_background [2018/10/21 15:12]
42.49.180.224 [Structure in experiment and data]
tutorial:shared:cluster_permutation_background [2017/08/17 11:21] (current)
127.0.0.1 external edit
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 In MEEG experiments,​ there are two types of UO: subjects and trials (i.e., epochs of time within a subject). Concerning the concept of a between- or a within-UO design, there are two schemes according to which the UOs can be assigned to the experimental conditions: (1) every UO is assigned to only one of a number of experimental conditions (**between** UO-design; **independent** samples), or (2) every UO is assigned to multiple experimental conditions in a particular order (**within** UO-design; **dependent** samples). Therefore, in a between-UO design, there is only one experimental condition per UO, and in a within-UO design there are multiple experimental conditions per UO. These two experimental designs require different test statistics. ​ In MEEG experiments,​ there are two types of UO: subjects and trials (i.e., epochs of time within a subject). Concerning the concept of a between- or a within-UO design, there are two schemes according to which the UOs can be assigned to the experimental conditions: (1) every UO is assigned to only one of a number of experimental conditions (**between** UO-design; **independent** samples), or (2) every UO is assigned to multiple experimental conditions in a particular order (**within** UO-design; **dependent** samples). Therefore, in a between-UO design, there is only one experimental condition per UO, and in a within-UO design there are multiple experimental conditions per UO. These two experimental designs require different test statistics. ​
  
-The two UO-types (**subjects** and **trials**) and the two experimental designs (between- and within-UO) can be combined and this results in four different types of experiments.+The two UO-types (**subjects** and **trials**) and the two experimental designs (between- and within-UO) can be combined and this results in four different types of experiments. ​ 
 ==== Computation of the test statistic and its significance probability ==== ==== Computation of the test statistic and its significance probability ====
 The statistical testing in FieldTrip is performed by the functions **[[reference:​ft_timelockstatistics|ft_timelockstatistics]]** and **[[reference:​ft_freqstatistics|ft_freqstatistics]]**. From a statistical point of view, the calculations performed by these two functions are very similar. These functions differ with respect to the data structures on which they operate: **[[reference:​ft_timelockstatistics|ft_timelockstatistics]]** operates on data structures produced by **[[reference:​ft_timelockanalysis|ft_timelockanalysis]]** and **[[reference:​ft_timelockgrandaverage|ft_timelockgrandaverage]]**,​ and **[[reference:​ft_freqstatistics|ft_freqstatistics]]** operates on data structures produced by **[[reference:​ft_freqanalysis|ft_freqanalysis]]**,​ **[[reference:​ft_freqgrandaverage|ft_freqgrandaverage]]**,​ and **[[reference:​ft_freqdescriptives|ft_freqdescriptives]]**. The statistical testing in FieldTrip is performed by the functions **[[reference:​ft_timelockstatistics|ft_timelockstatistics]]** and **[[reference:​ft_freqstatistics|ft_freqstatistics]]**. From a statistical point of view, the calculations performed by these two functions are very similar. These functions differ with respect to the data structures on which they operate: **[[reference:​ft_timelockstatistics|ft_timelockstatistics]]** operates on data structures produced by **[[reference:​ft_timelockanalysis|ft_timelockanalysis]]** and **[[reference:​ft_timelockgrandaverage|ft_timelockgrandaverage]]**,​ and **[[reference:​ft_freqstatistics|ft_freqstatistics]]** operates on data structures produced by **[[reference:​ft_freqanalysis|ft_freqanalysis]]**,​ **[[reference:​ft_freqgrandaverage|ft_freqgrandaverage]]**,​ and **[[reference:​ft_freqdescriptives|ft_freqdescriptives]]**.