Tam & Wong (accepted)[1] recently reported the invariance of the one-factor model of the Chinese version of the Toronto Alexithymia Scale-Short Form (TAS-9-C). This study sought to further examine the item-level equivalence of the TAS-9-C in a sample of Chinese adolescents across grade levels.

The present study is a sub-analysis of data collected between September 2008 and September 2009 (Tam & Wong, accepted). the TAS-9-C was administered to 500 Chinese adolescents. Differential item functioning (DIF) analysis was performed to identify any uniform and non-uniform difference on the nine TAS-9-C items among adolescents across different grade levels.

After a Bonferroni adjustment of p value (=0.0008, i.e., 0.05/63), results of DIF analyses showed that there is no uniform (all Fs ranging from 0.02–2.26, ps > 0.08) or non-uniform (all Fs ranging from 0.60–1.27, ps > 0.19) difference on the nine TAS-9-C items.

The four different grade level groups use the scale comparably, without showing any difference on item properties. Consistent with previous findings, no difference was observed in the performance on the nine TAS-9-C items among adolescents across grade levels. These findings further substantiate the use of TAS-9-C as a valid and reliable instrument among adolescents from a wide range of grade levels.

[1] Tam, B. K. H. & Wong, W. S. (accepted). Rasch analysis and item reduction of the Chinese version of the 20-item Toronto Alexithymia Scale (TAS-20-C) for adolescents. Paper to be presented at the 20th European Congress of Psychiatry, Prague, Czech Republic, 2012.