## 3 Proposed Method: Usability Textual Data Analysis (UTA)  
This study proposes usability textual data analysis (UTA) to extract usability problems by analyzing utterances obtained through usability tests based on a formal and unambiguous procedure. The formal and unambiguous analysis procedure can contribute to a usability evaluation with less confusion for the analyst and less omission of usability problems. The analysis procedure of UTA was inspired by the concept and coding procedure of SCAT and modified to fit the analysis purpose of extracting usability problems. Specifically, it is proposed to use the coding procedure in step (2) of SCAT and 70 design items [34] to extract usability problems from textual data obtained using the think-aloud protocol. SCAT is in line with the objectives of this study because of its formulaic and explicit analysis procedures and its applicability to small-scale data.  
In the proposed method, the analysts proceed according to the format shown in Table 1. The analysis is performed for each task of each participant in the usability test. It can also be analyzed by summarizing the verbal responses of each participant.  
First, an analyst transcribes the verbal data obtained from the user test and fills in the \"speech\" column of the format. Then, the analyst codes the data according to the steps described below and extract the problems. The overall flow and steps (1) and (2) are based on the SCAT method, and steps (3) and (4) incorporate a method for extracting usability problems using 70 design items.  
The coding procedure is as follows:  
1. Extraction of keywords
2. Keywords and phrasing should be described from the written text data. The keywords should be selected from the original text data to focus on considering usability problems and user requirements.
3. Paraphrase of keywords  
The words extracted in step (1) are paraphrased using specific and exact words. In this case, the words should be expressed using words other than those found in the text data.
4. Interpretation using 70 design items  
The concepts, phrases, and character strings that explain the previous section (keywords paraphrased with words outside the verbal data) are described. In this case, the 70 design items [34] are used to explain the previous section (keywords paraphrased with words outside of the verbal data).  
In the proposed method, 70 design items are used as a framework to explain the previous section. Since the 70 design items comprise a comprehensive list of items that should be considered when designing a product or system, the analyst can paraphrase the previous section without omission when targeting usability problems and user requirements. By applying the 70 design items, the analyst does not have to think about paraphrasing each item but can select appropriate items, which is efficient and reduces omissions. In addition, even novice designers can examine the 70 design items by referring to them.  
Extraction of problems based on the 70 design items  
Usability problems and user requirements are extracted based on the items that have been filled in so far and the original text data. Specific problem areas and situations are identified from the original text data, and the items entered in steps (1) and (2) and problem types are identified from the 70 design items entered in step (3). The usability problems and user requirements of the target product based on the 70 design items are extracted.  
Description of other items  
Any questions, issues, or hypotheses that should be considered during the user testing or analysis are described.