A waiver of consent may be appropriate to use in big data studies when: The cost of seeking and documenting consent from all of the subjects involved in the research may be prohibitive and would prevent the researcher from being able to conduct the research The research is more than minimal risk due to the sensitive nature of the data collected It is possible (and practicable) to reach all subjects whose information would be obtained and used for research purposes There are only a small (5-10) numbers of subjects involved