In the lower portion of each Chart, the Skeletal Age (Hand) of boy 34 and girl 2 may be similarly classified. There the middle one of the three curves denotes ``mean Skeletal Age'' for the Maturity Series boys and girls. The upper curve denotes the mean plus one standard deviation, and the lower curve represents the mean minus one standard deviation. Thus, a child's Skeletal Age ``dots'' may be classified as ``advanced'' when they appear above the middle curve, ``moderate'' when they appear immediately above or below the middle curve, and ``delayed'' when they appear below the lower curve.

To summarize the purpose of the Skeletal Maturity Chart: each contains two kinds of skeletal maturity norms which show two quite different methods of depicting developmental level of growth centers. First, the upper portion requires series of films for every child, consisting of those from Hand, Elbow, Shoulder, Knee, and Foot. The lower portion necessitates only films of Hand. Second, the upper portion permits comparison of maturity levels of an equal number of growth centers from the long, short, and round bones of the five regions. The lower portion permits comparison of maturity levels of short and round bones predominantly, since only two long bones are included in Hand and Wrist as a region. Third, the upper portion deals with only two indicators of developmental level, Onset and Completion. The lower portion utilizes the full complement of intermediate maturity indicators of each Hand center as well as their Onset and Completion. Fourth, the two indicators are for the most part widely separated chronologically, with the extensive age gap occurring during childhood for all but one growth center. The lower portion provides a rating at any stage between infancy and adulthood.