David L. Duewer and Dennis J. Reeder
Chemical Sciences and Technology Laboratory, National Institute of Standards and
Technology, Gaithersburg, MD
In collaboration with much of the North American DNA profiling community, we are characterizing the statistical properties of the RFLP measurement process. We have:
Combined with the NIST Standard Reference Material® 2390 band sizes for K562, we have used the above RFLP statistical properties to provide a data quality assessment process for the CODIS National DNA Index System.
Graphical display of highly replicate sizing data is an essential tool for our studies. Multiprobe scattergrams of "high band" vs. "low band" sizings from many different laboratories have proven particularly useful. Bivariate-normal summary distributions of the observed allele pair sizes enable recognition of a variety of events relating to measurement accuracy and precision, including: recognition of "outlier" data, software artifacts, identification of subtle sizing changes over time or protocol modifications, and intercomparison of population and casework performance.
In addition to monitoring K562 control sample measurements for CODIS submission, it is possible to develop displays appropriate for other control materials. We present the assumptions, techniques, and data requirements for building your own quality assurance models. All required calculations and graphical displays can be implemented in standard PC hardware using spreadsheet software.
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