2.1. Phase 1: translation and content validation of ITQ

The ITQ was translated and back-translated using the process suggested by Beaton, Bombardier, Guillemin, and Ferraz (2000); all items were translated from English to traditional Chinese by a bilingual technical writer, then back-translated by a bilingual study team member. Three other experts in mental health independently reviewed the initial forward and backward translations, and provided comments and wording suggestions for revision; two additional iterations of the translations were reviewed before a consensus was reached for the initial draft.

The Chinese-translated items were tested for content validity based on their relevance to the construct and their appropriateness in the Chinese culture (Polit & Beck, 2006; Polit, Beck, & Owen, 2007). An expert panel of two clinical psychologists, two mental health nurse researchers, and two social workers were invited to rate the relevance and appropriateness of each translated question on a 4-point Likert scale – ‘highly relevant/appropriate’ (4), ‘quite relevant/appropriate’ (3), ‘somewhat relevant/appropriate’ (2), and ‘not relevant/appropriate’ (1). Content validity indices were computed by item and for the overall scale to assess relevance and appropriateness. Item-level analysis was conducted using item content validity index (I-CVI), which is the proportion of experts who rated the item with a score of 3 or 4 (out of 4) (Polit & Beck, 2006). A modified kappa statistic (k*) was computed to correct for the chance agreement among experts that might artificially inflate the I-CVI ratings (Polit et al., 2007). Content validity index for the overall scale (S-CVI) was computed using an average I-CVI of all scale items (S-CVI_Ave) (Polit & Beck, 2006). For a panel of six raters, I-CVI and S-CVI_Ave are considered good when coefficient exceeds 0.78 and 0.90, respectively (Lynn, 1986; Polit & Beck, 2006); while k* >0.74 is considered excellent (Polit et al., 2007).

All translated items of the ITQ received excellent ratings on relevance and appropriateness, with I-CVIs ranging between 0.83 and 1.0, and k* between 0.82 and 1.0. Scale-level content validity was also high for both PTSD and CPTSD subscales, with S-CVI_Ave for relevance and appropriateness ranging between 0.92 and 1.00 for PTSD subscales and 1.00 for all CPTSD subscales. After content validation by expert panel, the Chinese ITQ was pilot tested with eight young adults recruited from a university setting; all participants gave positive comments on the clarity, understandability, and ease of answering the questions (Hinkin, 1998). The final Chinese ITQ was administered to a larger sample to assess its psychometric properties.