## 4 Case Study
### Analysing Failure Modes for IVIS  
#### 4.2.1 Evaluating Risk Parameters of Failure Modes for IVIS  
To evaluate the risk parameters of the identified failure modes, triangular fuzzy linguistic variables were adopted. The evaluation results of the seven team members (TM1-TM7) regarding occurrence, severity, and detection are given in Table 8, Table 9, and Table 10, respectively. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Failure Mode No.** & **Code in** & **Failure Mode** & **Failure Mode Description** & **Failure Mode Effect** & **Failure Mode Cause** \\ \hline
7 & 2.2.1.1 & A9 & Users are not aware of how to operate. & It is difficult to complete the task. & Be an unreasonable design. \\
8 & 2.3.1 & A4 & Users are not aware of how to operate. & It is difficult to complete the task. & The operation process is unreasonable. \\
9 & 2.2.2.4 & A9 & Users are unable to locate their & Impact on usability. & Be an unreasonable design. \\
10 & 2.4 & B & Users are unaware if the navigation has & Impact on usability. & Insufficient relevant clues. \\  & & & Users are unable to determine the & Results in incorrect operation. & The information architecture \\
11 & 3.1.2 & I2 & Correct method of operation. & Results in incorrect operation. & is complicated. \\
12 & 3.2.2 & R1 & Users are unable to locate the contract & Unable to complete the task. & Shortage of operational clues. \\
13 & 3.2.3 & C3 & Users select the wrong objects. & Unable to complete the task. & The meaning of icon is unclear. \\
14 & 3.4 & A8 & Users navigate back to the main interface & Impact on the following operations. & Shortage of operational clues. \\
15 & 3.2.1 & A9 & Users do not know how to navigate back. & Impact on the following operations. & Insufficient relevant clues. \\
16 & 3.2.1 & A2 & Users are not aware of how to operate. & Results in incorrect operation. & The layout of interface is unsuitable. \\
17 & 4.2.1 & A9 & Users have difficulty understanding & Unable to advance to the next step. & Overlooking users’ characteristics. \\  & & & Users are unclear about their & Results in incorrect operation. & Shortage of operational clues. \\
18 & 4.2.2 & B & Users are unclear about their & Results in incorrect operation. & The operation is complex. \\
19 & 4.3.1 & A9 & Users have difficulty understanding & Results in incorrect operation. & The meaning of words is unclear. \\  & & & & the meaning of words. & Unable to advance to the next step. & There are too many operational steps. \\
20 & 4.3.2 & A9 & Users are unable to figure out how to & Results in incorrect operation. & The meaning of words is unreasonable. \\
21 & 5.1.3 & I1 & Users are uncetrain about their next step. & Unable to advance to the next step. & There are too many operational steps. \\
22 & 5.1.4 & A4 & Users are unable to figure out how to & Results in incorrect operation. & The operation process is unreasonable. \\
23 & 5.2.1 & A9 & Users confuse the meaning of icons. & Unable to advance to the next step. & The meaning of icon is unclear. \\
24 & 5.2.3 & S2 & Users confuse the meaning of icons. & Results in incorrect operation. & The meaning of icon is unclear. \\
25 & 52.2.1 & A9 & Users are unclear about how to adjust & Unable to advance to the next step. & Shortage of operational clues. \\ \hline \hline \end{tabular}
\end{table} 
Table 7: _Cont._