The responses of 110 subjects to 18 items of the AT-20 tolerance of ambigui
ty scale were analyzed in an item response framework using Rasch modeling.
The results indicated that the items satisfy the assumptions of this model
and an excellent fit was obtained. In particular, the observed item reliabi
lity (KR-20) was 0.93 and the person reliability was 0.68. The latter value
agrees with previous findings derived in a classical test theoretical fram
ework. A Rasch type scale (M = 25, SD = 5) is developed and various psychom
etric and scaling issues are discussed. (C) 1999 Elsevier Science Ltd. All
rights reserved.