Bloodstain measurement using computer-fitted theoretical ellipses

Accuracy and precision are two key measurement components. Accuracy relates to a confidence level in similarity between known and measured values, and precision relates to similarity between repeated measures of the same standard. Measurements from spattered bloodstains interpolated within a mathematical framework make it possible to determine a blood source area of origin within three-dimensional space. The ability to accurately and precisely measure those spattered bloodstains increases confidence in the reliability of any origin determination. This paper describes an accuracy and precision study conducted on two methods of computer-assisted ellipse fitting (BackTrack Images and the newly developed Microsoft Office Excel 2003 AutoShapes) for bloodstain measurement purposes. The study, conducted in known and blind environments, demonstrates both methods of computer-assisted ellipse fitting to be robust and reliable bloodstain measurement techniques, particularly for those stains that have obliquely impacted a planar surface.