Updating methods for prediction models11 12
| Method | Updating method | Reason for updating |
| 0 | No adjustment (the original prediction model) | – |
| 1 | Adjustment of the intercept (baseline risk) | Difference in the outcome frequency (prevalence or incidence) between development and validation sample |
| 2 | Method 1 + adjustment of all predictor regression coefficients by one overall adjustment factor | Regression coefficients of the original model are overfitted (or underfitted) |
| 3 | Method 2 + extra adjustment of regression coefficients for predictors with different strength in the validation sample as compared with the development sample | As in method 2, and the strength (regression coefficient) of one or more predictors may be different in the validation sample |
| 4 | Method 2 + stepwise selection of additional predictors | As in method 2, and one or more potential predictors were not included in the original model, or a newly discovered marker may need to be added |
| 5 | Re-estimation of all regression coefficients, using the data of the validation sample only | The strength of all predictors may be different in the validation sample, or the validation sample is much larger than the development sample |
| 6 | Method 5 + stepwise selection of additional predictors | As in method 5, and one or more potential predictors were not included in the original model |