## 4 Case Study
### Results
#### 4.2.2 Network Analysis  
After applying network analysis to the co-occurrence matrix, the degree, betweenness, and eigenvector centralities of the nodes were extracted. Even though three centralities basically measure different properties of the network, high correlation coefficients among the centralities were recorded: 0.94 between degree and betweenness centralities, 0.87 between betweenness and eigenvector centralities, and 0.98 between degree and eigenvector centralities. Note that degree, betweenness, and eigenvector centrality respectively represent (1) the number of links incident on nodes, (2) the number of times a node acts as a bridge on the shortest path between two different nodes, and (3) relative scores of the number of important nodes to which a node is connected. As correlation coefficients turned out to be high, the lists of top-ranked nodes with respect to the three centralities were analogous (Table 1). Nodes such as convenience, gesture shape, fun, type of control, exactness, fatigue, desire to use, independent, range of motion, and repetitive ranked high among degree centralities. Each node was classified into two types: value dimensions and design variables. First, two criteria were used to identify a node as a design variable: (1) the node was a technical property of a product or service and (2) the node depends on the development of technology. For instance, because gesture \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Node** & **Degree \({}^{*}\)** & **Betweenness \({}^{*}\)** & **Eigenvector \({}^{*}\)** & **Node Type** \\ \hline Convenience & 53 (1) & 1262.8 (1) & 0.295 (1) & Value dimension \({}^{**}\) \\ Gesture shape & 48 (2) & 1192 (3) & 0.252 (2) & Design variable \\ Fun & 47 (3) & 1196 (2) & 0.23 (4) & Value dimension \({}^{**}\) \\ Type of control & 40 (4) & 672.4 (5) & 0.239 (3) & Design variable \\ Exactness & 39 (5) & 726.6 (4) & 0.222 (5) & Design variable \\ Fatigue & 34 (6) & 518.6 (7) & 0.222 (5) & Value dimension \({}^{**}\) \\ Desire to use & 33 (7) & 612.9 (6) & 0.202 (8) & Value dimension \\ Independent & 29 (8) & 412.7 (8) & 0.205 (7) & Value dimension \\ Range of motion & 27 (9) & 317.9 (11) & 0.166 (10) & Design variable \\ Repetitive & 26 (10) & 321.2 (10) & 0.18 (9) & Design variable \\ Novel & 26 (10) & 371 (9) & 0.161 (12) & Value dimension \\ Learnability & 26 (10) & 218.1 (16) & 0.159 (13) & Value dimension \\ Easy & 23 (13) & 205.3 (18) & 0.163 (11) & Value dimension \\ Various & 21 (14) & 232.5 (15) & 0.125 (17) & Design variable \\ Reaction time & 20 (15) & 183.1 (19) & 0.135 (14) & Design variable \\ Quality of life & 20 (15) & 271.6 (12) & 0.111 (20) & Value dimension \\ Familiar & 19 (17) & 148.8 (21) & 0.131 (16) & Value dimension \\ Compatibility & 19 (17) & 260 (14) & 0.114 (19) & Value dimension \\ Comfortable & 18 (19) & 123.5 (24) & 0.133 (15) & Value dimension \\ Suspicious & 17 (20) & 214.9 (17) & 0.099 (23) & Value dimension \\ Irritation & 17 (20) & 170 (20) & 0.094 (27) & Value dimension \\ Error & 15 (22) & 76.7 (29) & 0.12 (18) & Design variable \\ Stressful & 15 (22) & 141.1 (23) & 0.107 (21) & Value dimension \\ Daily & 15 (22) & 97.2 (25) & 0.099 (23) & Value dimension \\ Personalize & 15 (22) & 66.5 (31) & 0.091 (30) & Value dimension \\ \hline \hline \multicolumn{4}{l}{\({}^{*}\) The numbers in parentheses represent the ranks in the corresponding centrality. \({}^{**}\) Core value dimensions.} \\ \end{tabular}
\end{table} 
Table 1: Centrality of representative nodes and their types. shape and type of control are direct properties of gesture interaction, they were classified as design variables. Furthermore, exactness and reaction time are technical factors and hence also classified as design variables. Second, among value dimensions, a certain value dimension was regarded as a core value dimension if it turned out to be important. In this study, if the degree centrality of a node was more than 33 (i.e., the node connected to more than 25% of all nodes in the network), then the node was designated a core value dimension.