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.
Schlain
B
B
Ciba Corning Diagnostics Corp., Medfield, MA 02052.
Krouwer
J S
JS
D001322:Autoanalysis / Q000295:instrumentation / Q000592:standards*; D005188:False Negative Reactions; D006801:Humans; D007118:Immunoassay / Q000295:instrumentation*; D015233:Models, Statistical; D013223:Statistics as Topic; D013972:Thyrotropin / Q000032:analysis*
D013972:Thyrotropin