B Schlain | PubMed Health

PubMed1989

Multi-factor designs. II. A design for identifying instruments with sample-to-sample carryover and drift.

We describe a nearly orthogonal two-level design that involves use of a weighted analysis to estimate drift and very low amounts of sample-to-sample carryover simultaneously. Identifying systematic errors from these sources is especially important for assays of analytes presenting a large range and with a medical decision point close to zero. The design is illustrated with data for thyrotropin, where, in one run with 32 samples, 0.08% carryover was detected in the presence of concentration-dependent negative drift.

Autoanalysis↗

PubMed1988

A multi-factor experimental design for evaluating random-access analyzers.

A multi-factor experimental design for evaluating random-access analyzers has been developed and tested for the Ciba Corning "550 Express" random-access analyzer. The 12-sample design estimates imprecision, slope, nonlinearity, linear drift, and reagent carryover to the next assay. The design was constructed so that estimates of the factors' effects are almost entirely uninfluenced by each other. Use of the design is illustrated by an example in which reagent-to-assay carryover was pinpointed as an apparent cause of high imprecision. This led to a modification of the analyzer such that carryover was insignificant. The appendix contains a 27-sample design that provides additional estimates. Software to perform such calculations is available on request.

Aspartate Aminotransferases↗