Fig. 2
From: Fetal heart rate monitoring of short term variation (STV): a methodological observational study
Antenatal STV monitoring with Sonicaid™ vs EDAN™. Bland-Altman plot with limits of agreement (±1.96 SD, dotted lines), of STV values (n = 20) simultaneously derived with external (ultrasound) signal acquisition with two different brands of CTG monitors, Sonicaid™ and EDAN™. Mean difference was 0.6 msec (SD ±1.17). Spearman Rank Correlation STV Sonicaid vs delta STV (Sonicaid-EDAN) R = 0.35; p = 0.14