What percentage effort is reasonable for Biostatistics support on a research grant? The UC Davis Biostatistics Group says 10% as a bare minimum, 35-60% for straightforward projects with uncomplicated analyses, and 50-100%+ for large or complex projects. They give examples of large and complex projects: interim analysis, multi-site projects, development of novel statistical methods, and assembly of data from large, complex, or poorly documented administrative or survey data sets.
They also describe how to split the effort between a PhD Biostatistician, who supervises the overall effort, and a MS Biostatistician, who does most of the data management and statistical analysis.
Another point worth noting is that any grant listing less than 10% effort for a Biostatistician requires a special sign off.
UC Davis Biostatistics Group. Guidelines for estimating biostatistician effort and resources on grants. Available at http://ucdmc.ucdavis.edu/ctsc/area/biostatistics/Documents/UCD_Biostat_Effort_Guidelines.pdf or http://ucdmc.ucdavis.edu/ctsc/area/biostatistics/financialConsiderations.html.