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. Author manuscript; available in PMC: 2020 Feb 1.
Published in final edited form as: Sleep Health. 2018 Oct 28;5(1):18–22. doi: 10.1016/j.sleh.2018.09.003

Table 2.

PROMIS Sleep Disturbance 6-item Scale Internal Consistency Data

Scale Cronbach’s α: .86
Inter-item correlation:.50

Item Mean [SD] Corrected Item-Total Correlation Cronbach’s Alpha if Item Deleted
Quality Sleep 2.2 [.869] .67 .83
Refreshing 2.2 [.844] .57 .84
Problem with sleep 2.1[1.02] .71 .82
Difficulty falling asleep 1.9 [1.11] .65 .83
Restless 2.0 [1.10] .65 .83
Tried hard to get to sleep 1.9 [1.13] .63 .83