Testing of industrial products - Aggregates for construction

Precision values obtained from the cross-testing experiment on the Sand Equivalent test

Note 1. For all the tables here, "stragglers" have been included in the calculations, and "outliers" have been excluded.

Note 2. See the formulae for the special definition of coefficient of variation used with the Sand Equivalent test.

Table 1. Repeatability and reproducibility values.
		Level 1	Level 2	Level 3
Number of laboratories included	N	31	31	31
Average	X	40.1	55.5	57.2
Repeatability standard deviation	S_r1	0.92	1.00	1.17
Reproducibility standard deviation	S_R1	7.59	3.95	3.38
Critical range	W_c	3.2	2.9	3.4
Repeatability limit	r₁	2.6	2.8	3.3
Reproducibility limit	R₁	21.2	11.1	9.5

Table 2. Functional relations for Sand Equivalent test for SE values (X) in the range 40 <= X <= 60 SE units.
	Functional relationship
Repeatability standard deviation	S_r1 = 0.5 + 0.0108 (100 - X)
Reproducibility standard deviation	S_R1 = 0.5 + 0.0884 (100 - X)
Repeatability limit	r₁ = 1.4 + 0.03 (100 - X)
Reproducibility limit	R₁ = 1.4 + 0.25 (100 - X)

Table 3. Repeatability and reproducibility standard deviations expressed as coefficients of variation.
		Level 1	Level 2	Level 3
Repeatability coefficient of variation	C_r1	1.5	2.2	2.7
Reproducibility coefficient of variation	C_R1	12.7	8.9	7.9