Investigating error in saw mark minimum kerf width measurements

Area of Science:

• Forensic Anthropology
• Forensic Taphonomy
• Bioarchaeology

Background:

• Minimum kerf width (MKW) analysis aids in identifying tools used in skeletal sharp force trauma.
• Previous research on MKW and saw blade set width lacks comprehensive documentation of measurement error.
• Standardization of MKW measurement methods is needed for reliable forensic analysis.

Purpose of the Study:

• To assess the precision of MKW measurements.
• To quantify intraobserver and interobserver error in MKW data collection.
• To evaluate the impact of different measurement modalities on MKW accuracy.

Main Methods:

• 351 incomplete saw cuts from 27 saws were analyzed.
• MKW was measured using internal calipers, external calipers, and a digital stereo microscope.
• Intraobserver and interobserver error were calculated for each method using relative technical error of measurement (rTEM) and reliability coefficients.

Main Results:

• Internal calipers and stereo microscopes demonstrated the lowest intra- and interobserver error (rTEM 3.72–6.15%).
• External caliper measurements exhibited significantly higher error rates (intraobserver rTEM 8.53%, interobserver rTEM 21.32%).
• Higher measurement precision was observed between internal caliper and stereo microscope methods compared to external calipers.

Conclusions:

• Internal calipers and stereo microscopes provide more precise MKW measurements than external calipers.
• Variability in measurement techniques introduces significant error in skeletal trauma analysis.
• Standardized protocols for MKW measurement are essential for consistent and reliable forensic casework.