Reduction is a problem-solving strategy, relevant to various areas of computer science, and strongly connected to abstraction: a reductive solution necessitates establishing a connection among problems that may seem totally disconnected at first sight, and abstracts the solution to the reduced-to problem by encapsulating it as a black box. The study described in this article continues a previous, qualitative study that examined the ways undergraduate computer science students perceive, experience, and use reduction as a problem-solving strategy. The current study examines the same issue, but in the context of a larger population, using also quantitative analysis, and focusing on algorithmic problems. The findings indicate difficulties students have with the abstract characteristics of reduction and with acknowledging reduction as a general problem-solving strategy.