How does OPIS determine which shoes are in each level of stability?
Shoes are classified into the four levels of stability based on their Shoe Stability Index (SSI), the quantified amount of support that the shoe offers. Once calculated, the SSI values have been normalized to (approximately) a 100 point scale: shoes with a SSI value above 70 are Level 1 shoes, 60-69.9 are Level 2, 50-59.9 are Level 3, and those with a SSI under 50 are Level 4. While each level of stability includes a range of values, OPIS gives an accurate indication of how shoes in each stability level will perform. By maintaining these standards, OPIS also allows for the comparison of shoe models from one test period to another, or from one version of a shoe model to another!
