Diagnostic classification test for internet addiction (DCT-IA)

Given that most existing self-reported IA questionnaires can neither measure all the IA symptom criteria defined in the DSM-5, nor provide the information at the level of the IA symptom criteria, this study aims to develop a DCT-IA to measure the IA symptom criteria in the DSM-5 and to diagnose IA and diagnose the presence or absence of each symptom criteria.

The DCT-IA originally consisted of 181 items carefully selected based on the IA symptom criteria in the DSM-5 from ten self-rating inventories, including the IAT (Young, 1998a,b), Internet Related Problem Scale (IRPS; Armstrong et al., 2000), Pathological Use Scale (PIU; Morahan-Martin and Schumacher, 2000), Online Cognition Scale (OCS; Davis et al., 2002), Internet Addiction Test (IAT; Widyanto and McMurran, 2004), short version of IAT (s-IAT; Pawlikowski et al., 2013); also included four inventories developed by Chinese researchers, which are Adolescent Pathological Internet Use Scale (APIUS; Lei and Yang, 2007), Chinese Internet Addiction Scale (CIAS; Chen et al., 2003), Internet Addiction Scale (IAS; Yang and Zheng, 2008), and Computer Game Addiction Scale (CGAS; Liu and Li, 2007), respectively. These 181 selected items measure all nine IA symptom criteria in DSM-5. Items were modified to refer to the previous 12-month and to have consistent two response categories—yes or no. Each item measures at least one symptom. An item by criterion association matrix or Q-matrix (Tatsuoka, 1990), as shown in Table ​Table2,2, was constructed by twelve experts, who were divided into four groups with each group constructing about 46-item-Q-matrix. Each group includes two psychotherapists with more than 3 years of clinical experience on IA and one expert with 3-year research experience in the measurement of IA.

Q-matrix for the part items of DCT-IA.

Criterion S1 to S9 represents the nine symptom criteria for internet addiction defined in the DSM-5. Element 1 in row j and column k in the Q-matrix indicates that item j measures symptom k, whereas element 0 indicates that item j does not measure symptom k.

In the Q-matrix, entry 1 indicates a symptom criterion is measured by the item and entry 0 indicates not. The construction of Q-matrix was based on a Delphi method, including three steps. In Step 1, each expert defined the Q-matrix individually. In Step 2, the experts were anonymously provided with the decisions of the other experts in the same group and were told they could change their initial specifications. In Step 3, the three experts in each group met in person, and they discussed in detailed their opinions to form the consistent opinion. However, experts had diverse opinions toward the construction of 27 items. After deleting the 27 items, a 154 item-by-symptom Q-matrix was constructed, and per item measured an average of 1.46 symptom criteria and per symptom criteria was measured by an average of 14.1 items.

Table ​Table33 gives some item examples in the DCT-IA. Item “Use internet to avoid or alleviate helplessness, guilty or anxiety” measures “Use of Internet to escape or relieve a negative mood” (S8). While item “Even though there are times when I would like to, I can't cut down on” measures “Tolerance—the need to spend increasing amounts of time engaged in Internet” (S3) and “Unsuccessful attempts to control the participation in Internet” (S4).

Some item examples in DCT-IA.

Criterion S1 to S9 represents the nine symptom criteria for internet addiction defined in the DSM-5. Element 1 in row j and column k in the Q-matrix indicates that item j measures symptom k, whereas element 0 indicates that item j does not measure symptom k.