Table 1.

Results of the multiple comparisons applied to RMS values (Dunn Method) The test computes statistic Q, the number of rank sums, and shows whether P < 0.05 or not, for the pair being compared. P is the probability that the null hypothesis may be rejected and so concludes that there are differences between treatments. Diff of ranks is the difference in the rank sum orders being compared. The rank sums are a measure of the difference between two treatments.

	Pressure level 1			Pressure level 2
Comparison	Diff of Ranks	Q	P < 0.05	Diff of Ranks	Q	P < 0.05
Control vs Wood	1.500	4.743	Yes	1.800	5.692	Yes
Control vs Metal	0.340	1.075	No	1.900	6.008	Yes
Control vs Acrylic	0.960	3.036	Yes	2.300	7.273	Yes
Control vs Sandpaper	2.520	7.969	Yes	3.900	12.333	Yes
Wood vs Metal	1.160	3.668	Yes	0.100	0.316	No
Wood vs Acrylic	2.460	7.779	Yes	0.500	1.581	No
Wood vs Sandpaper	1.020	3.226	Yes	2.100	6.641	Yes
Metal vs Acrylic	1.300	4.111	Yes	0.400	1.265	No
Metal vs Sandpaper	2.180	6.894	Yes	2.000	6.325	Yes
Acrylic vs Sandpaper	3.480	11.005	Yes	1.600	5.060	Yes
	Pressure level 3			Pressure level 4
Comparison	Diff of Ranks	Q	P < 0.05	Diff of Ranks	Q	P < 0.05
Control vs Wood	2.820	8.918	Yes	2.500	7.906	Yes
Control vs Metal	1.580	4.996	Yes	1.620	5.123	Yes
Control vs Acrylic	1.560	4.933	Yes	0.700	2.214	No
Control vs Sandpaper	3.940	12.459	Yes	3.680	11.637	Yes
Wood vs Metal	1.240	3.921	Yes	0.880	2.783	No
Wood vs Acrylic	1.260	3.984	Yes	1.800	5.692	Yes
Wood vs Sandpaper	1.120	3.542	Yes	1.180	3.731	Yes
Metal vs Acrylic	0.020	0.0632	No	0.920	2.909	Yes
Metal vs Sandpaper	2.360	7.463	Yes	2.060	6.514	Yes
Acrylic vs Sandpaper	2.380	7.526	Yes	2.980	9.424	Yes