Imperial submitted a total of 1,257 staff across 14 units of assessment to the 2014 Research Excellence Framework (REF) assessment. In the REF results 46% of Imperial's submitted research was classified as 4*, 44% as 3*, 9% as 2* and 1% as 1*, giving an overall GPA of 3.36. In rankings produced by Times Higher Education based upon the REF results Imperial was ranked 2nd overall for GPA and 8th for "research power" (compared to 6th and 7th respectively in the equivalent rankings for the RAE 2008).

How many staff members did Imperial submit assessments of for the REF assessment?