\begin{tabular}{ll}33. & To be valid, an economic model must: \\ \hline 33. & b. be able to predict events occurring in the real world. \\ \hline\end{tabular}

To determine whether the statement "an economic model must be able to predict events occurring in the real world" is valid, we can analyze the characteristics of economic models. 1. **Definition of Economic Models**: Economic models are simplified representations of economic processes. They are used to understand, explain, and predict economic behavior and outcomes. 2. **Purpose of Economic Models**: The primary purpose of these models is to provide insights into how economies function and to forecast future economic events based on certain assumptions and variables. 3. **Predictive Capability**: For an economic model to be considered valid, it should ideally be able to make accurate predictions about real-world events. This predictive capability is crucial because it allows policymakers, businesses, and individuals to make informed decisions based on the model's outputs. 4. **Limitations**: However, it is important to note that while predictive capability is a significant aspect, it is not the only criterion for a model's validity. A model can still be useful even if it does not perfectly predict every event, as long as it provides valuable insights and explanations of economic phenomena. 5. **Conclusion**: Therefore, the statement that an economic model must be able to predict events occurring in the real world is generally true, but it should be understood within the context of the model's purpose and limitations. In summary, while the ability to predict real-world events is a key characteristic of a valid economic model, it is not the sole criterion for its validity.