1. Rasch analysis of the intermittent and constant osteoarthritis pain (ICOAP) scale 
B.J. Moreton, M. Wheeler, D.A. Walsh, N.B. Lincoln 
Osteoarthritis and Cartilage 
Volume 20, Issue 10, Pages (October 2012)
DOI: /j.joca
Copyright © 2012 Osteoarthritis Research Society International Terms and Conditions

2. Fig. 1
Person–item threshold distributions for the Constant subscale (a), Intermittent subscale (b) and Total scale (c). The top part of the graphs show the distribution of persons along the Rasch-transformed scale of constant, intermittent and total pain, respectively. The bottom part shows the distribution of items. Ideally, given good targeting, the two distributions should mirror one another such that the full range of trait expressed by participants is captured by the items on a scale.
Osteoarthritis and Cartilage  , DOI: ( /j.joca )
Copyright © 2012 Osteoarthritis Research Society International Terms and Conditions

3. Fig. 2
DIF across age groups for items 8 (a) and 9 (b) of the Total scale.
Osteoarthritis and Cartilage  , DOI: ( /j.joca )
Copyright © 2012 Osteoarthritis Research Society International Terms and Conditions