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Table 3 Summary of Rasch analysis results related to the FreKAQ, containing item-difficulty measures (with standard error, SE) and fit information

From: Cross-cultural adaptation, reliability and validity of the Fremantle Knee Awareness Questionnaire in Italian subjects with painful knee osteoarthritis

Item number and label

Measure (SE)

Infit

Outfit

MnSq

ZStd

MnSq

ZStd

1. My sore knee feels as though it is not part of the rest of my body

0.60 (0,10)

0.89

− 0.7

1.01

0.1

2. I need to focus all my attention on my sore knee to make it move the way I want it to

− 0.09 (0.08)

0.78

− 1.9

0.74

− 1.8

3. I feel as if my sore knee sometimes moves involuntarily, without my control

0.49 (0.09)

0.75

− 1.8

1.22

1.0

4. When performing everyday tasks, I don’t know how much my sore knee is moving

0.57 (0.10)

0.96

− 0.2

1.29

1.2

5. When performing everyday tasks, I am not sure exactly what position my sore knee is in

0.75 (0.11)

1.05

0.4

0.96

− 0.1

6. When my knee is hidden from view, I can’t perceive the exact outline of my sore knee

0.13 (0.09)

1.20

1.5

1.29

1.8

7. My sore knee feels larger than it appears

− 0.70 (0.09)

0.91

− 0.6

1.19

1.1

8. My sore knee feels smaller than it appears

− 0.85 (0.09)

1.11

0.8

1.11

0.7

9. My knees feel different between left and right (in terms of size and shape)

− 0.91 (0.09)

1.11

0.8

1.24

1.8

  1. Item difficulty is expressed in logit units, a logit being the natural logarithm of the ratio (odds) of mutually exclusive alternatives (e.g. higher response vs. lower response): zero logits represents mean item difficulty, and negative measures indicate higher frequency of occurrence with that statement (i.e. higher scores in that item)
  2. MnSq = mean-square statistics; ZStd = standardized z value