Many factors inhibiting and facilitating economic growth have been suggested. Can agnostics rely on international income data to tell them which matter? We find that agnostic priors lead to conclusions that are sensitive to differences across available income estimates. For example, the PWT 6.2 revision of the 1960-96 income estimates in the PWT 6.1 leads to substantial changes regarding the role of government, international trade, demography, and geography. We conclude that margins of error in international income estimates appear too large for agnostic growth empirics.