Observer variation in spirometry.
The intra-observer and inter-observer variation associated with clinical spirometry was statistically analyzed. The technical errors for the MEFR and MMF measurements were large enough to question their clinical reliability, especially in borderline instances. Measurement differences between two observers, as in this study, are statistically significant. This observation has special meaning for groups engaged in epidemiologic studies. Significant inter-individual variation will diminish the quality of pooled results.
Chronic respiratory disease among nonsmokers in Hagerstown, Maryland. II. Problems in the estimation of pulmonary function values in epidemiological surveys.
Abstract Prediction equations for the FEV 1.0 and PEFR in a population of white male nonsmokers are presented. Data are also presented to demonstrate the superiority, for epidemiological purposes, of the maximum pulmonary function value in a series of trials over the mean of the sequence. Statistically significant and sizable instrument and interviewer effects were found, and a technique for taking these effects into account is presented. Analysis of published data suggested that the relationship of pulmonary function values to weight, chest expansion and diameter, and hand grip strength should be reinvestigated. Factors influencing the variability of an individual's pulmonary function values are discussed. The importance of these questions to the design and analysis of longitudinal studies of pulmonary function values is emphasized.
Laminar heat or mass transfer in rectangular channels and in cylindrical tubes for fully developed flow: comparison of solutions obtained for various boundary conditions
Abstract A comparison is made of results obtained with various boundary conditions at the wall of the channels. By comparing blood Sherwood numbers for finite wall resistance with those for constant concentration boundary condition only a small variation is found for various points along the blood channel.