Different methodologies for computing total annual hours worked are adopted across G7 statistical offices to estimate productivity, and, therefore, we cannot be sure about international comparisons of productivity. This paper describes the design, implementation, and results of an online randomised controlled experiment to assess the impact of communicating this uncertainty in comparing productivity between the UK and the other G7 countries. The online survey results support the proposed communication tools as an effective way of conveying the uncertainty on the estimates of the international comparison of productivity for the UK public. They are effective even for respondents with limited knowledge of what productivity is. But communication tools are likely to be more helpful to members of the public that are familiar with the concept as they are better at making an inference based on the communicated data.