Table 2.
Principal component analysis, item-total correlation, logit measure and fit statistics (n = 559)
| Fit statistics | ||||||
| Scale/item | Component loadings | Item-total correlation | Logit measurea (error) | Infit MNSQ | Outfit MNSQ | |
| Physical functioning | ||||||
| 1 | Lifting heavy objects | .69 | .68 | -0.15 (0.08) | 1.00 | 1.05 |
| 2 | Running | .62 | .60 | 2.69 (0.07) | 1.18 | 1.17 |
| 3 | Walking on uneven ground | .67 | .68 | 0.75 (0.07) | 0.87 | 0.90 |
| 4 | Walking five miles | .70 | .69 | 1.95 (0.07) | 1.14 | 1.10 |
| 5 | Walking one mile | .71 | .74 | 0.29 (0.07) | 1.11 | 1.04 |
| 6b | Walking 100 yards | .68 | .72 | -1.62 (0.11) | 0.87 | 0.81 |
| 7 | Crossing the road | .67 | .68 | -2.25 (0.14) | 0.92 | 0.81 |
| 8b | Bending down | .53 | .55 | 0.62 (0.07) | 1.36 | 1.37 |
| 9 | Kneeling down | .63 | .63 | 2.25 (0.07) | 1.00 | 0.98 |
| 10 | Standing for one hour | .71 | .72 | 0.52 (0.07) | 1.09 | 1.07 |
| 11 | Standing for five minutes | .66 | .66 | -1.56 (0.12) | 0.94 | 0.85 |
| 12 | Going up several flights of stairs | .77 | .79 | 1.09 (0.07) | 0.71 | 0.72 |
| 13 | Going up one flight of stairs | .75 | .78 | -0.43 (0.08) | 0.71 | 0.73 |
| 14 | Going down several flights of stairs | .75 | .75 | 0.88 (0.07) | 0.78 | 0.79 |
| 15 | Going down one flight of stairs | .73 | .75 | -0.36 (0.08) | 0.74 | 0.73 |
| 16 | Getting into a sitting position | .67 | .68 | -1.24 (0.10) | 1.02 | 0.97 |
| 17b | Staying seated for two hours | .55 | .53 | 0.01 (0.08) | 1.55 | 1.50 |
| 18b | Staying seated for 15 minutes | .58 | .59 | -1.49 (0.12) | 1.11 | 0.94 |
| 19b | Getting up from a sitting position | .65 | .67 | -0.35 (0.08) | 0.99 | 1.00 |
| 20b | Getting in or out of the bath or shower | .71 | .73 | -0.55 (0.08) | 0.89 | 0.89 |
| 21 | Getting in or out of bed | .67 | .68 | -1.06 (0.09) | 0.92 | 0.96 |
| Activity limitations | ||||||
| 22 | Knee slowing you down | .62 | .76 | 0.69 (0.07) | 0.69 | 0.74 |
| 23b | Avoid turning/twisting/sideways moves | .57 | .56 | 1.66 (0.07) | 1.23 | 1.40 |
| 24 | Interference with travel | .56 | .71 | -0.88 (0.08) | 1.29 | 1.24 |
| 25b | Interference with sleep | .50 | .64 | -0.72 (0.07) | 1.38 | 1.41 |
| 26 | Interference with work | .59 | .78 | 0.31 (0.07) | 0.79 | 0.80 |
| 27b | Interference with hobbies, etc | .62 | .51 | 1.52 (0.07) | 1.30 | 1.27 |
| 28b | Interference with family life | .59 | .80 | -0.46 (0.07) | 0.66 | 0.65 |
| 29 | Interference with social activities | .56 | .81 | -1.11 (0.08) | 0.80 | 0.77 |
| 30 | Interference with doing errands | .53 | .80 | -1.02 (0.08) | 0.83 | 0.80 |
| Emotional functioning | ||||||
| 31 | Time spent thinking about knee | .64 | .71 | 1.34 (0.07) | 0.84 | 0.94 |
| 32 | Angry or annoyed | .73 | .74 | 0.61 (0.07) | 0.83 | 0.78 |
| 33 | Downhearted and low | .78 | .80 | -0.23 (0.07) | 0.82 | 0.80 |
| 34 | Worried about knee worsening | .78 | .73 | 0.97 (0.07) | 0.90 | 0.85 |
| 35b | Embarrassed or self-conscious | .62 | .68 | -1.16 (0.08) | 1.17 | 1.10 |
| 36 | Bad temper or grumpy | .72 | .76 | -1.14 (0.08) | 0.77 | 0.77 |
| 37 | Frustrated | .69 | .75 | 0.38 (0.07) | 0.76 | 0.74 |
| 38b | Worry about future | .79 | .73 | 0.64 (0.07) | 0.90 | 0.94 |
| 39b | Worry about money | .60 | .58 | -1.03 (0.09) | 1.62 | 1.58 |
| 40b | Think that you are getting old | .52 | .39 | -0.38 (0.08) | 1.79 | 1.87 |
a Logits of lower magnitude represent decreasing quality of life.
b Item removed from final version.