Random assignment without tears: How to stop worrying and love the Cambridge randomizer

Objectives: This note describes a low-cost online portal called "the Cambridge Randomizer", which enables treatment providers to conduct random assignment themselves, while the researcher still maintains control over the entire process and the integrity of the allocation process. Methods: Discussion of the advantages and disadvantages of the tool; case studies of experiments in which the Cambridge Randomizer is used are explored, with an emphasis on error rate assessment. Results: Treatment providers and researchers alike can log in securely to the Randomizer, assess eligibility of potential cases, provide instantaneous baseline information for each case, and automatically assign cases to treatment and control conditions. The Randomizer automatically sends an electronic report to the research team with each assignment, thus increasing the control over each assignment. Conclusions: The Cambridge Randomizer is a user-friendly research tool. Low error rate and continuous researcher control over the randomization process are particularly attractive, especially in trickle-flow assignment experiments. Experimentalists are encouraged to use this and similar tools that would reduce the overall costs of studies without adverse impacts to the research integrity