Graphical Tools for RFLP Measurement Quality Assurance: Single-Locus Charts

Abstract

Forensic restriction fragment length polymorphism analyses typically provide two results for each sample, one result for each unique allele, at each genetic locus probed. In collaboration with the member laboratories of the Technical Working Group for DNA Analysis Methods, we have developed graphical techniques that compactly summarize even large numbers of such paired measurements. This paper provides a detailed description of the basic tool, a modified bivariate control chart for data from one sample at one locus. We demonstrate how various modifications and combinations of these "single-locus charts" can be used for within-and among-laboratory quality assurance activities.

Polymerase Chain Reaction Amplification of DNA from Aged Blood Stains: Quantitative Evaluation of the “Suitability for Purpose” of Four Filter Papers as Archival Media

“…Figure displays all pairwise comparisons of standardized average peak areas among the five treatments; the standardized heights (data not shown) show very similar patterns. All of the comparisons are well described as bivariate normal distributions using the 70-sample average and standard deviations of each of the involved treatments and the bivariate correlation coefficient between them 6 Pairwise comparisons of standardized Ampf𝓁STR COfiler areas.…”

Multiplex_QA: An exploratory quality assessment tool for multiplexed electrophoretic assays

“…3, with each unique pair of metrics plotted in its own panel. The ellipse in each panel should enclose about 95% of the pairs of representative values, assuming both metrics are approximately normally distributed [18]. In addition to the very strong positive correlation between H/A 250 and R 187 , both may be positively correlated with the signal intensity.…”

Graphical Tools for RFLP Measurement Quality Assurance: Laboratory Performance Charts

“…The design and construction of the single-locus chart (SLC), typically displaying data from many laboratories for a single sample at a single locus, has been presented previously (7). The laboratory performance chart (LPC), displaying data for one laboratory for multiple samples at multiple loci, can be regarded as an overlay of many SLCs with each overlay displaying only data for one laboratory.…”

“…We previously described a graphical tool, termed the singlelocus chart (SLC), for displaying large amounts of RFLP data for a given sample at a given genetic locus (7). With two modifications, the basic components of the SLC can be used to create a laboratory performance chart (LPC) for each participant in an among-laboratory comparison exercise.…”