Table 5.

Reproducibility and validation of models

Topic	% (n = 47) articles
Model validation included	34 (16)
Validation dataset*
Same data (bootstrap)	13 (6)
Same population, new data**	23 (11)
External (that is, new population setting)	11 (5)
Larger series including original sample	0 (0)
Validation of models
Final model with same coefficients and variables	26 (12)
Unclear reporting	9 (4)
Modifications suggested to model in light of validation?	0 (0)

* Five studies included validation with more than one dataset.

** Methods used by studies were as follows: five studies used a random split, two used temporal split, five used cross validation, one used the jacknife method. Two studies used two and three methods respectively.