Orthodontic research often involves collection of data on a cohort of subjects with longitudinal follow-up. For example, the study of the growth of facial profiles among boys and girls usually uses data from repeated tracings of cephalometric landmarks across childhood and adolescence. Analysis of longitudinal data is a challenging task and usually requires advanced statistical methods that might not be familiar to most orthodontic researchers. After the research questions are carefully formulated, appropriate methods are then selected according to the properties of the data, such as the number of repeated measurements for each subject, the time intervals between measurements, and the shape of the growth curves. (Source: American Journal of Orthodontics and Dentofacial Orthopedics)
MedWorm: Dentistry