ISQ Questionnaire Revision: Addressing Dimension Clarity and Item Selection

The EFA indicated that in the primary version of the ISQ, which included 18 items, the dimensions were not clearly defined. Some items showed significant overlap across different dimensions. Therefore, the questionnaire items were reselected. The criteria for removing items were as follows: (1) Items that caused strong negative emotions such as fear and disgust. (2) Items that induced intense itching, which were difficult to imagine due to limited personal experience. The reasons for removing such items were as follows: (1) The ISQ requires participants to minimize the influence of emotions on their ratings. (2) Imagining and rating itching sensations in unfamiliar scenarios may lead to significant biases. In the end, items I2, I3, I7, I14, and I17 were removed, and the remaining items formed the new version of the ISQ. The EFA results for the primary and new ISQ can be found in Table 5. The new ISQ has been divided into three dimensions, with each item's factor loading greater than 0.5 in its respective dimension, and no issues of co-factors. The cumulative explained variance of the three dimensions is 63.68%, which is higher than that of the primary ISQ (See Table 4).