TLMSchartmaker is a program to fit smooth gentile curves to reference data using the LMS method.
Reference gentile curves show the distribution of a measurement as it changes according to some covariate, e.g. age. The LMS method summarizes the changing distribution by three curves representing the median (M), coefficient of variation (S) and skewness (L), the latter expressed as a Box-Cox power. Using penalized likelihood the three curves can be fitted as cubic splines by non-linear regression, and the extent of smoothing required can be expressed in terms of smoothing
parameters or equivalent degrees of freedom.
The process involves five stages: data entry, model fitting, graphical display, model checking and model saving, with the last four stages repeated as often as necessary. Data editing and graph editing are also available from menu Edit.