Table 3.

LoE assignment guidelines

LoE	Temporality	Analogy	Mechanism	Reproducibility	Specificity	Coherence
4—Speculative	X	X
3—Weak	X	X	X for 1 or 2 of these
2—Moderate	X	X	X	X	X
1—Strong	X	X	X	X	X	X

Numerical assignments for LoE are determined based on the Hill guidelines. An LoE is assigned as speculative if it meets both the temporality and analogy criterion. The addition of any one or two of the mechanisms, reproducibility, or specificity criteria justifies an assignment of weak LoE, whereas all 3 criteria are necessary for a moderate LoE. A strong LoE must meet all six criteria⁶.