Table 3 Summary of the validation error categories along with the suggested guideline and potential erroneous data selection methods
Validation error | Representative data | Non-representative data |
|---|---|---|
1. Follow-up period and reference standard | 3-year follow-up | 1-year follow-up |
2-year follow-up | ||
4-year follow-up | ||
3. Temporal selection | Balanced selection for each calendar year (2008–2019) | Early cases (2008–2012) and late controls (2015–2019) |
Early control (2008–2012) and late cases (2015–2019) | ||
5. Population characteristics: Age | Representative age distribution (40–74) | Post-menopause cases (>55) and pre-menopause controls (≤55) |
Pre-menopause cases (≤55) and post-menopause controls (>55) | ||
7. Population characteristics: Mammographic density | Representative mammographic density distribution | Density A and B |
Density C and D | ||
Density A, B and C | ||
10. Cancer characteristics | Representative distribution | Invasive only |
In situ only | ||
12. Image acquisition (equipment manufacturer) | GE data | Philips calibration |
Philips data | GE calibration | |
Balanced multivendor data | GE case and Philips controls | |
Philips case and GE control |
