The experimental errors in measuring the size of bones in mice

Abstract

An experiment was conducted with 236 mice (3-9 weeks of age) to determine the bias in taking soft-X-ray photograph, and systematic and random errors of the values measured with a picture analyzer. Sites measured are length of scapula (SCAL), humerus (HUML), ulna (ULNL), coxae (COXL), femur (FEML), tibia (TIBL), thoracic vertebrae (VTL), lumbar vertebrae (VLL) and sacral vertebrae (VSL), and width of scapula (SCAW) and coxae (COXW). Systematic bias peculiar to the procedure was found in the values of bones measured. The X-ray photograph caused the downward bias to the length of sacral vertebrae alone, but did not to others. The standard errors of measurements (squared root of error variance) with picture analyzer ranged between 0.12 and 0.24 mm and had no apparent relationship to the size of bone.