Group effect of time intervals for the rest and postural condition. a&d Tremor intensity (TI). b&e Maximal power (Powmax). c&f Frequency of maximal power (Freqpowmax). PD = Parkinson’s disease group. REF = healthy reference group. Due to the homogeneity of the REF-group, the inter quartile range (IQR) of the TI and Powmax are very low and thus concealed by the markers. * = significant within group difference from interval 1 (P ≤ 0.0167). # = significant difference between groups at all intervals (P ≤ 0.0167).