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Table 35 Precision estimates for measuring percent round in Type 1 samples by various methods Repeatability STD, % Reproducibility STD, % Method of Measurement-- No. of Sample Type Labs 1s d2s 1s d2s Roundometer--Type 1 11 2.5 7.1 3.8 10.6 COM-A b/l--Type 1 6 0.7 2.0 1.5 4.2 COM-A SPHT--Type 1 3 1.2 3.4 1.7 4.7 COM-B--Type 1 4 4.3 12.1 7.0 19.7 Type 1 glass beads and only one laboratory reported round of three 100-g Type 3 glass bead replicates size measurements of Type 3 and Type 5 glass beads. measured by participating laboratories. Since preci- sions for the Type 3 glass beads as measured by the Roundness Measurements COM-B device could not be developed with the one available dataset, the comparison of the precision esti- Type 1 Samples mates was made between the mechanical roundo- Precision estimates of the percent roundness in meter and the COM-A SPHT and b/l parameters. As the #50 size class for the Type 1 samples for various shown in Table 36, the COM-A b/l and SPHT param- methods of measurement are provided in Table 35. eters provided comparable repeatability and repro- The precision estimates are based on the roundness of ducibility precisions and these precisions were both three 50-g Type 1 glass bead replicates measured by significantly smaller than those for the roundometer. participating laboratories. As indicated by Table 35, the COM-A b/l parameter provided the least within- Type 5 Samples and between-laboratory variability among the four Precision estimates of the percent round in the methods of measurement. #14 size class of Type 5 samples for various methods of measurement are provided in Table 37. The preci- Type 3 Samples sion estimates are based on the percent round of Precision estimates of the percent roundness in three 200-g Type 5 glass bead replicates measured by the #18 size class for the Type 3 samples for various the participating laboratories. Because the precision methods of measurement are provided in Table 36. for the Type 5 glass beads as measured by the single The precision estimates are based on the mass percent COM-B instrument could not be developed with one Table 36 Precision estimates for measuring percent round in Type 3 samples by various methods Repeatability STD, % Reproducibility STD, % Method of Measurement-- No. of Sample Type Labs 1s d2s 1s d2s Roundometer--Type 3 8 2.3 6.4 4.1 11.5 COM-A b/l--Type 3 8 0.9 2.5 1.0 2.9 COM-A SPHT--Type 3 4 0.9 2.4 1.1 3.1 Table 37 Precision estimates for measuring percent round in Type 5 samples by various methods Repeatability STD, % Reproducibility STD, % Method of Measurement-- No. of Sample Type Labs 1s d2s 1s d2s Roundometer--Type 5 8 1.8 4.9 4.5 12.5 COM-A b/l--Type 5 8 0.6 1.7 1.2 3.5 COM-A SPHT--Type 5 4 1.1 3.0 1.5 4.2 18