What is essential in developing Overall Rates (OARs) according to the described model?

To develop Overall Rates (OARs) effectively within the described model, stratifying properties and determining net profit is essential. This process involves categorizing properties into distinct groups, or strata, based on similarities such as property type, location, and value characteristics. By doing so, appraisers can ensure that the analysis is tailored to the nuances of each property type, which enables a more accurate calculation of rates.

Determining net profit is also vital because it provides insight into the economic performance of the properties within each stratum. This information helps in establishing fair and equitable OARs that reflect the true value of the properties based on their income-generating potential. Without appropriate stratification and an understanding of net profitability, the rates derived may not accurately represent the market conditions, leading to potential discrepancies in property assessments.

While other options might play a role in the overall assessment process, they do not specifically address the foundational requirement of categorization and economic performance analysis that is critical in developing OARs. Therefore, the focus on stratifying properties and determining net profit stands out as a key component in this context.