THE first of any series of blood-pressure measurements is commonly thought to be higher than subsequent measurements, and is therefore considered untrustworthy. Many physicians unwilling to trust a single measurement use either the mean or the lowest of a number of readings taken in direct succession or at intervals during a half-hour interview or physical examination. A typical procedure is that recommended by Oliver,2 but many different procedures are in general use, and their variations are not customarily regarded as causing major differences in the worth of the estimation of blood-pressure.The untrustworthiness of the first determinations is variously attributed to psychic effects, effects of manipulation of the arm, effects of rest, effects of posture, and the confusion introduced by such transient changes in blood-pressure as the respiratory variation and the Traube-Hering waves. This report is an attempt to determine the part played by these several factors in a series of determinations made for the purpose of estimating the precision of measurement obtainable in this laboratory-a necessary assessment as a foundation for other studies in blood-pressure.Gallavardin and Haour [1912] made a hundred careful measurements of this decrement, and the distribution of their findings is sufficiently similar to those of the present study to suggest that they were probably measuring the same phenomena. But, whereas they attribute the initially high value to stimulation by the cuff and imply that it is 1 The statistical work involved in this presentation was performed with the help of the Works

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Patients with syncope while sitting or standing should undergo the tilting table test to determine whether the cause is neurocardiogenic so that pacemaker implantation can be avoided. The majority of patients with NS can be successfully treated by drugs. But in some patients pacemaker implantation may have to considered if drug treatment has failed.

Statistical analysis of 16,320 blood‐pressure measurements by three observers on 130 subjects has led to the following conclusions applicable to the conditions, subjects, and observers detailed in the text:— 1. When the effects of temporal differences and differences between the two arms are eliminated, systematic differences between the observers in this experiment are insignificant. 2. Significant differences in the variability of determination made by different observers were found. 3. The probable error of measurement of a single blood‐pressure observation is 1·2–1·8 mm. for systolic pressures and 1·8–2.· mm. for diastolic pressures when readings are made under conditions of rest and adequate time is permitted for the establishment of postural equilibrium. 4. The gain in precision obtained by averaging successive readings is greater for diastolic pressure than systolic pressure. 5. An average of more than 5 observations of blood‐pressure does not result in a useful gain in precision. Grateful acknowledgment is made by the authors to the Works Progress Administration (O.P. No. 465–03–3–631, Unit A‐8) for clerical assistance in the analysis of the data. For statistical advice and criticism of the manuscript we are indebted to Dr. Herbert S. Conrad and Dr. Robert C. Tryon.