SIM Comparison of DC Resistance Standards at 1 $\Omega$ , 1 $\hbox {M}\Omega$ , and 1

A set of regional comparisons of the dc resistance standards at the nominal values of 1 Omega, 1 MOmega, and 1 GOmega has recently been completed in the Sistema Interamericano de Metrogia (SIM) region. The motivation, design, standards, and results of these regional comparisons are reported. The resistance standards were characterized for drift rate, temperature coefficient, pressure coefficient, and voltage coefficient so that the participants would be able to measure the transport standards using procedures routinely used in their calibration services. Data that show the transport behavior of several standards are also presented. The pilot and participant laboratory data sets were used to determine a linear regression for each transport standard. The comparison reference values (CRVs) are reported, and each participant´s difference from the CRV at each nominal value is reported at 1 Omega, 1 MOmega, and 1 GOmega. The linking of the regional comparison results at 1 Omega and 1 GOmega to bilateral and key comparison results is also reported. Degrees of equivalence for nonlinking SIM laboratories are reported with respect to key CRVs.