Table 4

Assessment of relative power and connectivity differences on occipital electrodes between the PPR and non-PPR groups

Measure	Node	Uncorrected p-value	U statistic	z-score	Effect size	CI lower limit	CI upper limit
Relative low alpha power	O1	0.79	575	−0.81	−0.028	−0.095	0.047
Relative low alpha power	O2	0.74	582	−0.65	−0.013	−0.089	0.049
Relative alpha power	O1	0.86	562	−1.10	−0.078	−0.13	0.049
Relative alpha power	O2	0.80	573	−0.85	−0.039	−0.14	0.041
Occipital connectivity	O1	0.94	543	−1.52	−0.76	−2.18	0.48
Occipital connectivity	O2	0.76	580	−0.70	−0.34	−2.18	1.17

The relative power was computed following the methods of Vaudano et al. (2017). We considered the following two frequency bands: low alpha power (6–9 Hz) as in the main analysis; and alpha power (7.5–12.5 Hz) as in the study by Vaudano et al. (2017). The occipital connectivity corresponds to the connection strength of the electrodes (i.e., sum of in-strength and out-strength; Rubinov and Sporns, 2010). The p-values, U statistics, and z-scores correspond to one-sided Mann–Whitney U tests assessing whether the relative power (or connectivity strength) is higher in the PPR group relative to the non-PPR group at a given occipital electrode. All p-values are not significant. The effect size (median difference) and confidence intervals further show that there are no statistical differences between the groups when using these measures.