# Neurofeedback Effects on EEG Connectivity among Children with Reading Disorders: I. Coherence
## 2 Materials and Methods
### Statistical Analysis  
Because the sample size was not very large, the Kolmogorov-Smirnoff test was performed to assess the normality of the distributions. None of the cognitive variables had a normal distribution in either of the two groups (TD and RD groups) in the first stage. In the second stage, none of the cognitive variables had a normal distribution in either of the two groups (NFB and Sham treatment groups) for either of the two conditions (before and after). The theta/alpha ratio did not satisfy the normality assumption for either of the two groups (NFB and Sham treatment groups) in either of the two conditions (before and after). Regarding the coherence variables, approximately 35% did not have a normal distribution. Considering that for multivariate normal data, the marginal distributions and linear combinations should also be normal, the use of parametric statistical analysis was not appropriate. Nonparametric methods do not require theoretical distributions because the null-hypothesis distribution of statistical tests is created by iteratively shuffling the data [80]. The data of this study had a multivariate nature, so correction for multiple comparisons was necessary. Bonferroni and false discovery rate (FDR) approaches are more conservative methods to avoid the inflation of type I and type II errors [81; 82] compared to the nonparametric permutation test implemented by [PERSON] in the LORETA software [21]. In this study, a nonparametric permutation test [83] was used. The following comparisons were performed: (1) comparison between RD and TD groups, (2) comparison between NFB and Sham groups regarding the before vs. after changes, and (3) independent comparison before vs. after treatment in each of the treated groups (NFB or Sham). [PERSON]'s d statistic was computed for all significant results. 2.8.1. RD Group vs. TD Group  
Analyses were performed for the following variables or sets of variables: reading accuracy, reading comprehension, reading speed, interhemispheric coherence, and intrahemispheric coherence. Analyses were carried out using a nonparametric \(t\)-test for independent samples with 5000 permutations. 2.8.2. NFB vs. Sham Groups Regarding Pre-Post Treatment Changes in Children with RDs  
Null hypotheses H0: A1-A2 = B1-B2 was tested, where A denotes the NFB group and B denotes the Sham group; 1 and 2 represent after and before treatment, respectively. Variables or sets of variables tested were reading accuracy, reading comprehension, reading speed, theta/alpha ratio, interhemispheric coherence, and intrahemispheric coherence. Analyses were carried out using a nonparametric \(t\)-test for dependent samples with 5000 permutations. 2.8.3. Pre-Post Treatment Comparisons for Each Group (NFB or Sham)  
Independent analyses for each group were performed for the following variables or sets of variables: reading accuracy, reading comprehension, reading speed, theta/alpha ratio, interhemispheric coherence, and intrahemispheric coherence. Analyses were carried out using a nonparametric \(t\)-test for dependent samples with 5000 permutations. 3.1. Comparison between Children with RDs and Children with Typical Development  
3.1.1. Intrahemispheric Coherence  
In Figure 2, the results of intrahemispheric coherence in both hemispheres can be observed. In the left hemisphere, the group made up of children with RDs obtained higher delta coherence values in F3-P3 (t = \(-\)2.9712, \(p\) = 0.0497, d = 0.702) than the children with TD. In the theta frequency band, the RD group also presented higher values than the TD group in F3-P3 (t = \(-\)3.0414, \(p\) = 0.0384, d = 0.724), F3-O1 (t = \(-\)3.1413, \(p\) = 0.0290, d = 0.728), and P3-O1 (t = \(-\)2.9475, \(p\) = 0.0472, d = 0.720).