g_glf

vector of standardized scores from the continuous ordinal scale, 0

vector of 3 elements: <code>M</code>, the offset, <code>B</code>, the slope of the curve, and <code>T</code>, the symmetry of the curve

A parametric version of the g function following Richards (1959):
$$g(v) = M + \frac{1}{B} \log\left(\frac{Tv^T}{1-v^T}\right)$$

logistic

Richards

A regression framework for response variables which are continuous self-rating scales such as the Visual Analog Scale (VAS) used in pain assessment, or the Linear Analog Self-Assessment (LASA) scales in quality of life studies. These scales  measure subjects' perception of an intangible quantity, and cannot be handled as ratio variables because of their inherent nonlinearity. We treat them as ordinal variables, measured on a continuous scale. A function (the g function, currently the generalized logistic function) connects the scale with an underlying continuous latent  variable.  The link function is the inverse of the CDF of the assumed underlying distribution of the latent variable. Currently the logit link, which corresponds to a standard logistic distribution, is implemented.

g_glf: Generalized logistic g function

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