Fig. 4

Statistical charts of tremor amplitudes of 7 DOFs in joints in 8 subjects. The tremor amplitude was the peak value between 2 to 7 Hz of the PSD. The average tremor amplitude of different trials of three time periods of 7 DOFs in joints in one subject are separately presented as bars (error bars: standard deviation). “n” denotes the total number of trials. The Wilcoxon signed-rank test was employed to show the differences of tremor amplitude between the time periods. The alternative hypothesis: P _p is greater than P _s , P _p is not equal to P _a , and P _s is not equal to P _a . *0.01 < p < 0.05; **p < 0.01. P _p : tremor intensity prior to stimulation; P _s : tremor intensity during stimulation; P _a : tremor intensity after stimulation