Table S6. Step 1 of calculation of standard error of measurement (SEM) using from data from Table S5: obtaining 2-factor analysis of variance data output (SPSS software). Relevant output is in black.

Tests of between-subjects effects, dependent variable: LVEDD
Source	Type III sum of squares	Degrees of freedom (df)	Mean square (MS)	F	Sig.
Corrected model	43	59	0.730	34.0	0.000
Intercept	2,890	1	2,890.125	134,648.8	0.000
Observers (O)	4	2	2.061	96.0	0.000
Subjects (S)	38	19	2.012	93.7	0.000
Observer × subject interaction (O × S)	1	38	0.019	0.9	0.630
Error	1	60	0.021
Total	2,935	120

LVEDD, left ventricular end-diastolic dimension. Measurements per observer per subject. Number of: o =3; n=20; m =2.