# Differences

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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 2018/10/22 13:25 robert old revision restored2018/10/21 15:12 [Structure in experiment and data]2017/08/17 11:21 external edit2016/03/05 11:11 2014/05/20 22:02 [Computation of the test statistic and its significance probability] 2011/07/13 10:07 [The multiple comparisons problem] 2011/06/29 11:06 lilla 2010/04/07 09:28 timeng ft_prefix2010/01/28 11:04 2009/04/07 11:46 ingrid 2009/04/07 11:45 ingrid 2009/04/06 21:47 ingrid 2009/04/06 21:20 ingrid created 2018/10/22 13:25 robert old revision restored2018/10/21 15:12 [Structure in experiment and data]2017/08/17 11:21 external edit2016/03/05 11:11 2014/05/20 22:02 [Computation of the test statistic and its significance probability] 2011/07/13 10:07 [The multiple comparisons problem] 2011/06/29 11:06 lilla 2010/04/07 09:28 timeng ft_prefix2010/01/28 11:04 2009/04/07 11:46 ingrid 2009/04/07 11:45 ingrid 2009/04/06 21:47 ingrid 2009/04/06 21:20 ingrid created Both sides next revision Line 16: Line 16: 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]]**.