In the context of product development, determining when to rely on data or research is crucial, and four heuristics can guide this decision: the product stage, user-base size, type of problem (Tylenol vs. Vitamin), and cultural context. Data is beneficial for products with large user bases or post-product/market fit, while research is more effective for smaller user bases or pre-product/market fit to understand user pain points. Tylenol problems, which users are aware of, can be addressed with data and research, whereas Vitamin problems, which users aren't actively seeking solutions for, require a visionary approach. Cultural nuances can render both methods ineffective if not understood, highlighting the need for a combination of data analysis and user research to identify and solve user problems in unfamiliar cultural contexts. These heuristics provide a framework to balance quantitative and qualitative inputs for effective product strategy, adapting to the complexity of real-world scenarios.