Popper has argued that the repetition of tests yields diminishing returns. His argument has been criticised by Musgrave for involving an inductive element. This paper argues that Musgrave's solution robs the concept of corroboration of it's force. An alternative solution is suggested on the basis of a differentiation between replication and repetition. It is argued that one then does receive diminishing returns in agreement with the structure of corroboration in general.