Startups have a high rate of failure and they fail because entrepreneurs invest their resources based on poorly tested assumptions. This is a waste of costly time and resources. In this research, a framework named the Experimentation Machine is developed that helps entrepreneurs to adopt assumption-driven entrepreneurship. If entrepreneurs use the Experimentation Machine, it is expected that they become more familiar with assumption-driven entrepreneurship, and possibly even more successful as startups. The framework has been evaluated with seven startups, who used the Experimentation Machine over a period of 10 weeks. Our findings confirm that startups benefit from the framework and that it enabled them to quicker unearth (incorrect) assumptions.