A method of determining a subject's corrected precordial ECG amplitude in an ECG measurement, comprising the steps of (a) providing said subject's ECG data obtained from a first ECG measurement made at a first time point in paper form or stored on a memory device, wherein said ECG was recorded using a standardized and reproducible electrode placement method, and wherein said ECG data comprises data for a six lead V1-V6 precordial ECG; (b) providing said subject's ECG data obtained from a second ECG measurement made at a second time point, which is after the first time point in paper form or stored on a memory device, wherein said ECG was recorded using a standardized and reproducible electrode placement method, and wherein said ECG data comprises data for a six lead V1-V6 precordial ECG and a precordial ECG amplitude A; and (c) determining a percentage correction value R by determining the position of the transition zone in said data of a six lead V1-V6 precordial ECG from said first ECG measurement in paper form or stored on a memory device and assigning to it a percentage correlation value R1, and determining the position of the transition zone in said data of a six lead V1-V6 precordial ECG from said second ECG measurement in paper form or stored on a memory device and assigning to it a percentage correlation value R2, wherein R1 or R2 is independently (i) about -30% in case the transition zone is between lead V1 and lead V2, (ii) about -20% in case the transition zone is around lead V2, (iii) about -10% in case the transition zone is between lead V2 and lead V3, (iv) about 0 in case the transition zone is around lead V3 or between lead V3 and lead V4, (v) about 10% in case the transition zone is around lead V4, (vi) about 20% in case the transition zone is between lead V4 and lead V5, (vii) about 30% in case the transition zone is around lead V5, and (viii) about 40% in case the transition zone is between lead V5 and lead V6; and calculating the percentage correction value R using formula R = R2 − R1; and (d) calculating a subject's corrected precordial ECG amplitude A* from a precordial ECG amplitude value A from said ECG measurement from said second time point, and the percentage correction value R, using formula A ∗ = A + R × A; thereby determining a subject's corrected precordial ECG amplitude in an ECG measurement, and providing said subject's corrected precordial ECG amplitude in an ECG measurement in paper form or via a display. (a) providing said subject's ECG data obtained from a first ECG measurement made at a first time point in paper form or stored on a memory device, wherein said ECG was recorded using a standardized and reproducible electrode placement method, and wherein said ECG data comprises data for a six lead V1-V6 precordial ECG; (b) providing said subject's ECG data obtained from a second ECG measurement made at a second time point, which is after the first time point in paper form or stored on a memory device, wherein said ECG was recorded using a standardized and reproducible electrode placement method, and wherein said ECG data comprises data for a six lead V1-V6 precordial ECG and a precordial ECG amplitude A; and (c) determining a percentage correction value R by determining the position of the transition zone in said data of a six lead V1-V6 precordial ECG from said first ECG measurement in paper form or stored on a memory device and assigning to it a percentage correlation value R1, and determining the position of the transition zone in said data of a six lead V1-V6 precordial ECG from said second ECG measurement in paper form or stored on a memory device and assigning to it a percentage correlation value R2, wherein R1 or R2 is independently (i) about -30% in case the transition zone is between lead V1 and lead V2, (ii) about -20% in case the transition zone is around lead V2, (iii) about -10% in case the transition zone is between lead V2 and lead V3, (iv) about 0 in case the transition zone is around lead V3 or between lead V3 and lead V4, (v) about 10% in case the transition zone is around lead V4, (vi) about 20% in case the transition zone is between lead V4 and lead V5, (vii) about 30% in case the transition zone is around lead V5, and (viii) about 40% in case the transition zone is between lead V5 and lead V6; and calculating the percentage correction value R using formula R = R2 − R1; and (i) about -30% in case the transition zone is between lead V1 and lead V2, (ii) about -20% in case the transition zone is around lead V2, (iii) about -10% in case the transition zone is between lead V2 and lead V3, (iv) about 0 in case the transition zone is around lead V3 or between lead V3 and lead V4, (v) about 10% in case the transition zone is around lead V4, (vi) about 20% in case the transition zone is between lead V4 and lead V5, (vii) about 30% in case the transition zone is around lead V5, and (viii) about 40% in case the transition zone is between lead V5 and lead V6; (d) calculating a subject's corrected precordial ECG amplitude A* from a precordial ECG amplitude value A from said ECG measurement from said second time point, and the percentage correction value R, using formula A ∗ = A + R × A; thereby determining a subject's corrected precordial ECG amplitude in an ECG measurement, and providing said subject's corrected precordial ECG amplitude in an ECG measurement in paper form or via a display.