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Table 2 Reliability coefficients

From: Refining sleep measurement using the Motionwatch8©: how many days of monitoring do we need to get reliable estimates of sleep quality for older adults with mild cognitive impairment?

   Intraclass Reliability Coefficients (95% CI) Days of Monitoring Required to Achieve Acceptable Reliabilities of
   1 Day 4 Days 7 Days 14 Days 0.7 0.8 0.9
All Participants
(N = 151)
Sleep Duration 0.46
(0.40, 0.52)
0.71
(0.63, 0.78)
0.84
(0.80, 0.88)
0.92
(0.89, 0.93)
2.74 4.70 10.57
Fragmentation Index 0.55
(0.49, 0.61)
0.82
(0.76, 0.86)
0.90
(0.87, 0.92)
0.94
(0.93, 0.95)
1.91 3.27 7.36
Sleep Efficiency 0.63
(0.57, 0.68)
0.83
(0.78, 0.87)
0.92
(0.90, 0.94)
0.96
(0.95, 0.97)
1.37 2.35 5.29
Sleep Latency 0.33
(0.27, 0.39)
0.40
(0.23, 0.55)
0.73
(0.66, 0.79)
0.86
(0.83, 0.89)
4.74 8.12 18.27
Wake After Sleep Onset 0.64
(0.59, 0.70)
0.85
(0.81, 0.89)
0.93
(0.91, 0.94)
0.96
(0.95, 0.97)
1.31 2.25 5.06
Older Adults without Mild Cognitive Impairment
(N = 69)
Sleep Duration 0.52
(0.43, 0.62)
0.75
(0.64, 0.84)
0.86
(0.81, 0.91)
0.93
(0.91, 0.95)
2.15 3.69 8.31
Fragmentation Index 0.44
(0.35, 0.54)
0.75
(0.63, 0.83)
0.85
(0.79, 0.90)
0.91
(0.88, 0.94)
2.97 5.09 11.45
Sleep Efficiency 0.61
(0.53, 0.70)
0.82
(0.74, 0.88)
0.91
(0.87, 0.94)
0.95
(0.94, 0.97)
1.49 2.56 5.75
Sleep Latency 0.31
(0.23, 0.41)
0.37
(0.08, 0.58)
0.73
(0.62, 0.82)
0.85
(0.80, 0.90)
5.19 8.90 20.03
Wake After Sleep Onset 0.58
(0.50, 0.67)
0.83
(0.76, 0.89)
0.91
(0.88, 0.94)
0.95
(0.93, 0.95)
1.69 2.90 6.52
Older Adults with Mild Cognitive Impairment
(N = 82)
Sleep Duration 0.40*
(0.32, 0.49)
0.65*
(0.51, 0.76)
0.80
(0.73, 0.86)
0.90
(0.86, 0.93)
3.50 6.00 13.50
Fragmentation Index 0.61**
(0.53, 0.69)
0.84*
(0.78, 0.89)
0.91*
(0.88, 0.94)
0.95**
(0.94, 0.97)
1.49 2.56 5.75
Sleep Efficiency 0.64
(0.57, 0.72)
0.84
(0.77, 0.89)
0.92
(0.89, 0.95)
0.94
(0.92, 0.96)
1.31 2.25 5.06
Sleep Latency 0.35
(0.27, 0.44)
0.48
(0.28, 0.65)
0.73
(0.63, 0.81)
0.87
(0.83, 0.91)
4.33 7.43 16.71
Wake After Sleep Onset 0.68*
(0.61, 0.75)
0.86
(0.81, 0.91)
0.93
(0.91, 0.95)
0.97*
(0.95, 0.98)
1.10 1.88 4.24
  1. *Marginally different from older adults without Mild Cognitive Impairment (p < 0.10)
  2. **Significantly different from older adults without Mild Cognitive Impairment (p < 0.05)