An observer's variable error in skeletal age assessment of hand RGs (i.e., the irregular ion between independent readings of the same film) was studied on 1,124 readings of 326 films from 233 children aged 16 months to 17 years. seventy-nine of the RGs were full-size reproductions in Macyr's Nutrition and Chemical Growth in Childhood; the remainder were actual films of children in Halifax, Canada (healthy Orphanage residents and children examined in a nutrition survey).
There was no significant difference in variable error associated with the atlas (Todd, Greulich-Pyle), age of child, sex, differences between skeletal and chronologic age, differences between children, or differences between RGs of the same child, except for a tendency in the Macy Series for the poorest reproductions to have a larger variable error than the best reproductions. ions. In most readings the individual indicators were assessed separately and the results averaged, but a quicker method (over-all appraisal) did not produce a significantly different variable error. The quick method may be useful in large surveys, although it appears too coarse for the study of individual children.
The observer's variable error was expressed by standard deviations of approximately three months (Macy Series—both atlases; Nutritirn Series—Greulich-Pyle atlas) and four months (Orphanage Series—both atlases). With a standard deviation of three months an assessor must affix an error of ± 8.3 months to his estimate of a child's progress in skeletal age, in order to obtain confidence limits with 95% probability. If his standard deviation is four months he must allow ± 11.1 months. For evaluation of the assessment method, many observers' estimates of variable error are needed, and an appeal for data is issued.
After more than 1200 readings had been made the observer's practice lapsed for about a year. Reassessment of a random sample of RGs then showed, besides variable error, a mean systematic difference of approximately three months from the previous readings of the same films with the same atlas. To avoid this risk, any two films that are to be assessed for skeletal progress should be read within a few weeks of each other, and special precautions are therefore necessary to secure independence of the two readings.
Comparison and Correlation between Ultrasonography and Radiography in Skeletal Age Assessment of Children Less than Six Years of Age, based on Greulich & Pyle Atlas Method
