Expected severity stratum | Mayo Clinic stratum | Total videos | |||||||
Normal | 0 | 1–2 | 3–5 | 6–7 | 8–9 | 10–11 | Most severe | ||
Core videos | 5 | 4 | 6 | 8 | 8 | 8 | 6 | 5 | 50 |
Core videos assigned to each investigator | 2* | 2 | 2 | 3 | 3 | 3 | 2 | 2 | 19 |
Duplicates of core video assigned to investigators | – | – | Each investigator was assigned two videos that duplicated two core videos from among these strata | – | 2 | ||||
Contact friability videos (One with CFT, one without CFT) | – | – | 2 | 2 | 2 | 2 | 2 | – | 10 |
CFT videos assigned to each investigator | – | – | Each investigator was assigned two CFT pairs, where the CFT+ videos were nominally in these strata. | – | 4 | ||||
Total readings assigned to each investigator | 2* | 2 | 2–4 | 3–5 | 3–5 | 3–5 | 2–4 | 2 | 25 |
One of the videos in the normal stratum was later found to be from a patient, thus there were truly four screening colonoscopies in this stratum.
↵* Owing to a video error in this stratum, five readers viewed one instead of two normal videos.
CFT, Contact Friability Test.