Table 4 |
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|
Cronbach's alpha (internal consistency reliability) and average inter-variable correlation for the 4 factors |
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|
Factor* |
n (obs)† |
n (variables)‡ |
Cronbach's alpha |
Average inter-variable correlation |
|
|
||||
|
IP/CMC |
2047 |
20 |
0.95 |
0.51 |
|
MCP |
2081 |
8 |
0.81 |
0.35 |
|
Knee |
1451 |
4 |
0.85 |
0.59 |
|
Spine |
1917 |
10 |
0.80 |
0.29 |
|
|
||||
|
*IP/CMC factor: Thumb IP, DIP 2-5, PIP 2-5, CMC1; MCP factor: MCP 2-5, Knee factor: TFJ and PFJ; Spine factor: Disc space narrowing and osteophytes L1/2 to L5/S1. †Number of observations with data for a factor ‡Number of radiographic variables included in a factor CMC, carpometacarpal joint; DIP, distal interphalangeal joint; IP, interphalangeal joint; MCP, metacarpophalangeal joint; PFJ, patellofemoral joint; PIP, proximal interphalangeal joint; TFJ, tibiofemoral joint. |
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|
Nelson et al. Arthritis Research & Therapy 2011 13:R176 doi:10.1186/ar3501 |
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