True models do not exist; see René Margritte’s famous painting ‘La trahison des images’ (The Treachery Of Images).
The Treachery of Images; René Magritte, 1928–29; Oil on canvas;
63.5 × 93.98 cm, 25 × 37 in;
Los Angeles County Museum of Art, Los Angeles, California
Table 6.1 shows results from analyses of 1.2 million elderly patients undergoing surgery. A practical exercise outlines the underlying analyses (SPSS, can also be done in R of course).