Differential item functioning of the Chinese version of the somatosensory amplification scale among adolescents across grade levels

Introduction: Tam et al. (2011)[1] recently reported the invariance of the one-factor model of the Chinese version of the Somatosensory Amplification Scale (ChSAS). The objective of this paper is to further examine the item-level equivalence of the ChSAS in a sample of Chinese adolescents across grade levels. Methods: The ChSAS was administered to 500 Chinese adolescents. Differential item functioning (DIF) analysis was performed to identify any uniform and non-uniform differences on the 10 ChSAS items among adolescents across different grade levels. Results: After a Bonferroni adjustment of p value (=0.0007, i.e., 0.05/70), results of DIF analyses showed that there is no uniform (all Fs ranging from 0.17–2.15, ps > 0.09) or non-uniform (all Fs ranging from 0.47–1.76, ps > 0.02) difference on the 10 ChSAS items. Conclusions: The four different grade level groups used the scale comparably, without showing any difference on item properties. These findings further substantiate the use of ChSAS as a valid and reliable instrument among adolescents across grade levels. Copyright © 2013 Elsevier Masson SAS.