A collection of some drawbacks experienced by most risk analysis methods:

1. Slight variations between similar projects/medical devices. Difficulty estimating variations and their magnitude and impact.
2. Synergistic effects of several, combined risks. 1 + 1 = 3.
3. Information gaps. Many of these methods were developed decades ago.
4. Telling whether a risk is major or minor.
5. For experiments, there are no universal standards (lb. vs. kg).
6. Are often complex and need a trained profession to perform and understand.