Reproducibility of peak expiratory flow measurements. 
The ease of PEF measurement and the availability of inexpensive, portable instruments have led to its increasing use.  However, relatively little literature exists addressing the testing procedure, optimal frequency, instrument precision, and virtually no epidemiologic literature exists describing the variability of repeated PEF tests within a single test session (reproducibility).  A summary of data from one of the authors' own worker population studies is presented which addresses precision of PEF measurement.