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Digit ratios (2D:4D) determined by computer‐assisted analysis are more reliable than those using physical measurements, photocopies, and printed scans
Author(s) -
Allaway Heather C.,
Bloski Terri G.,
Pierson Roger A.,
Lujan Marla E.
Publication year - 2009
Publication title -
american journal of human biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.559
H-Index - 81
eISSN - 1520-6300
pISSN - 1042-0533
DOI - 10.1002/ajhb.20892
Subject(s) - calipers , intraclass correlation , reliability (semiconductor) , nuclear medicine , limits of agreement , medicine , reproducibility , mathematics , statistics , power (physics) , physics , geometry , quantum mechanics
Prenatal androgens influence the second to fourth digit ratio (2D:4D) of hands with men having lower ratios than women. Numerous methods are used to assess 2D:4D including, physical measurements with calipers, and measurements made from photocopies, scanned images, digital photographs, radiographs, and scaled tubes. Although each method appears relatively reliable, agreement upon a gold standard is necessary to better explore the putative effects of prenatal androgens. Our objective was to assess the level of intra and interobserver reliability when evaluating 2D:4D using four techniques: (1) physical measurements, (2) photocopies, (3) printed scanned images, and (4) computer‐assisted image analysis. Physical measurements, photocopies, and printed scanned images were measured with Vernier calipers. Scanned images were also measured with computer‐based calipers. Measurements were made in 30 men and 30 women at two different time points, by three experienced observers. Intraclass correlation coefficients were used to assess the level of reliability. Intraobserver reliability was best for computer‐assisted (0.957), followed by photocopies (0.939), physical measurements (0.925), and printed scans (0.842; P = 0.015). Interobserver reliability was also greatest for computer‐assisted (0.892), followed by photocopies (0.858), physical measurements (0.795), and printed scans (0.761; P = 0.001). Mean 2D:4D from physical measurements were higher than all other techniques ( P < 0.0001). Digit ratios determined from computer‐assisted, physical measurements, and printed scans were more reliable in men than women ( P = 0.009, P = 0.017, and P = 0.012, respectively). In summary, 2D:4D determined from computer‐assisted analysis yielded the most accurate and consistent measurements among observers. Investigations of 2D:4D should use computer‐assisted measurements over alternate methods whenever possible. Am. J. Hum. Biol., 2009. © 2009 Wiley‐Liss, Inc.