Final answer:
The Health Maintenance Organization (HMO) models consist of the Staff, Group, Network, and IPA models, with the IPA model historically being one of the more popular models due to its flexibility and broad network of practitioners.
Step-by-step explanation:
Health Maintenance Organization (HMO) Models
The Health Maintenance Organization (HMO) models in the marketplace differ in terms of structure and operation. When addressing the question of which model is predominant, we consider four types: the Staff model, the Group model, the Network model, and the IPA model (Independent Practice Association).
Each HMO model has distinct features:
IPA model: Physicians maintain their own practices but also contract with an HMO through an association or network.
While it's difficult to definitively say which model is predominant as market presence can vary by region and over time, historically, the IPA model has often been one of the more popular models. It allows for flexibility and a broad network of practitioners which can be advantageous for coverage.