The RiskAssessment.basis is the input used within the risk assessment. The resource lacks support for the resulting coefficients, weights, impact, or % contribution assigned by the algorithm.

In some cases, the basis is more specific (e.g. condition code) than what the risk score algorithm outputs. The method/algorithm can be proprietary, such that the top drivers are often assigned a coefficient, weight, or % contribution to help explain why the risk score is what it is when the details of the method/algorithm are proprietary.

Examples:

Milliman MARA outputs the clinical risk drivers (http://www.millimanriskadjustment.com/clinical-risk-drivers/), which are used to see "how various disease and medical condition impact the clinical portion of risk scores"

Verisk's top risk drivers are output as a ranked list of condition categories (e.g. diabetes, cancer, etc.) influencing the risk score.