Table 3.

Statistical assessment of sampling frequency

			SAMPLING FREQUENCY [Hz]
			250	125	83.3	62.5	50	41.7	35.7	31.3
AMPLITUDE	num	p	1.000	0.966	0.681	0.859	0.977	0.435	0.114	0.067
		R2	1.000	0.998	0.997	0.997	0.995	0.994	0.992	0.989
	fit	p	1.000	0.991	0.987	0.966	0.958	0.959	0.948	0.878
		R2	1.000	1.000	1.000	1.000	1.000	1.000	0.999	0.999
DURATION	num	p	1.000	0.507	0.126	0.001	1e-06	1e-10	1e-15	1e-18
		R2	1.000	0.847	0.802	0.772	0.761	0.675	0.661	0.462
	fit	p	1.000	0.979	0.957	0.963	0.955	0.173	0.260	0.004
		R2	1.000	0.993	0.979	0.956	0.902	0.839	0.887	0.543
PEAK VEL.	num	p	1.000	0.004	0.001	1e-06	1e-08	1e-11	1e-14	1e-15
		R2	1.000	0.932	0.924	0.910	0.902	0.906	0.893	0.892
	fit	p	1.000	0.981	0.987	0.951	0.963	0.803	0.557	0.034
		R2	1.000	0.997	0.994	0.981	0.930	0.197	0.938	0.864

The Table shows the results of a statistical test to assess the robustness of the measurements of saccadic parameters (amplitude, duration and peak velocity) at decreasing sampling frequency of the eye position data, from 250 Hz (original), down to 31.3 Hz. The used eye movement data are those from Experiment 2. For each parameter, the table reports the p value of a two-sided Wilcoxon rank-sum test, against the null hypothesis that parameters measured on the original and subsampled traces come from a distribution with the same median. Statistically significant values are highlighted in bold characters. The table also reports the coefficient of determination R², computed between the parameters measured on the original sampling frequency and those measured on the subsampled traces