Figure 1.

A simple example illustrating the procedure of multivariable fractional polynomial method. Firstly, predictors are arranged in descending order of significance. The most important predictor is assessed by closed test for its inclusion and fractional polynomial (FP) function. The procedure proceeds sequentially for all predictors. The second cycle begins by examining the second predictor for its inclusion and FP function. Other predictors are kept in their FP form obtained from cycle 1. The procedure concludes when two cycles converge.