An algorithm for finding the linear region in a nonlinear data set.

Finding the linear reportable range is an important procedure for each method in clinical chemistry. One is often called upon to limit the reportable range in order to find the linear region. Limiting the reportable range by visual techniques is subjective, may introduce bias and is not programmable.

The usefulness of calibration verification and linearity surveys in predicting acceptable performance in graded proficiency tests.

Objective: To assess the association between performance on graded chemistry surveys and evaluation of linearity and calibration in Linearity surveys.

Design: Data from Linearity Surveys (LN series) and from routine comprehensive College of American Pathologists chemistry surveys (all series) were used to evaluate the hypothesis that laboratories with nonlinear or univerified calibration would have a greater likelihood of unacceptable performance on comprehensive chemistry surveys.

Results: This study found that acceptable calibration verification evaluation is significantly related to acceptable rates for most analytes, including albumin, calcium, chloride, glucose, iron, magnesium, sodium, total bilirubin, uric acid, high-density lipoprotein cholesterol, triglycerides, alkaline phosphatase, alanine and aspartate aminotransferase, digoxin, gentamicin, phenobarbital, procainamide, and thyroxine.

College of American pathologists experience with the linearity surveys, 1987-1991.

The Instrumentation Resource Committee has offered a survey since 1988 to perform and evaluate linearity. The survey uses a serum-based material and satisfies federal regulations that require linearity evaluations in the clinical laboratory. Both statistical and empirical methods to determine linearity were developed for the survey.

Focusing on the laboratory, not the computer.

Much time and effort is spent comparing laboratory computer systems; the process is not unlike that of shopping for an automated chemistry analyzer. But the authors believe too little effort is expended in examining and understanding the laboratory functions that are to be computerized and, as a consequence, computer purchases fail to reach expectations. Here, they emphasize the importance of evaluating laboratory functions, particularly the area of communication and record keeping.