# FlickPose: A Hand Tracking-Based Text Input System for Mobile Users Wearing Smart Glasses
## 5 Experiments to Evaluate Text Input System
### Experimental Results  
First, we explain the character input speed, the number of deletions, and the number of consecutive deletions used as evaluation indices in this study. Words per minute (WPM) and characters per minute (CPM) are generally used to calculate character input speed, which represent the number of words or characters entered per minute, respectively. They can quantitatively measure the input speed of sentences composed of English letters and hiragana, but the task sentences used in this study contain alphanumeric characters and kanji characters in addition to hiragana and thus include key inputs that are not reflected in the number of characters, such as conversion keys and mode-switch keys. Therefore, in this study, the number of keystrokes required to input the task text in the shortest time was divided by the time taken to input the text to calculate the character input speed. The number of deletions is calculated as the number of characters deleted during the input of the task sentence. In addition, when the same task sentence is being input, consecutive deletions may occur, and the maximum of those values is calculated as the number of consecutive deletions for that task sentence. For example, if a single character is deleted twice, two characters are deleted once, and three characters are deleted once during the input of a certain task sentence, the number of deletions is seven and the number of consecutive deletions is three. The reason for calculating the number of consecutive deletions is to measure the ease of checking the input field during the input process. If the user only looks at the keyboard when inputting text, even if an error occurs, the user will not be able to check the input field until it is too late, which will delay the detection of the error, and thus multiple deletions will be necessary. On the other hand, if the text input system allows the user to easily check the input field, or if the user can input text while keeping his/her eyes on the input field, the number of consecutive deletions is expected to be smaller, because the user can detect the input error at an early stage. Next, the values for each evaluation index calculated based on the log data are described. Table 7 shows the average values and the standard deviation of the char \begin{table}
\begin{tabular}{c l} \hline \hline \multicolumn{2}{c}{**Question**} \\ \hline Q1 & How fired do you feel in your arms after the experiment? \\ \hline Q2 & Did you find the input system used in this project easy to use? \\ \hline Q3 & Did you find the screen structure of the input system used in this project easy to read? \\ \hline Q4 & Did you find the hand pose easy to remember? \\ \hline Q5 & Were there any hand pose misjudgments during input? \\ \hline Q6 & Were there any button selection errors during input? \\ \hline Q7 & Did you find it easy to type hiragana-only sentences? \\ \hline Q8 & Did you find it easy to type hiragana + alphanumeric sentences? \\ \hline Q9 & Did you find it easy to type hiragana + kanji sentences? \\ \hline Q10 & Do you think that using this method in the future will result in higher input speed and accuracy than now? \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Survey questions. acter input speeds of the ten subjects for each task and overall. From Table 7, the hiragana + alphanumeric task has the lowest average character input speed per task for all methods. The standard method has the highest average for all tasks at 37.26, followed by the raycast method and the touch-panel method, in that order. Comparing the average values of the standard method and the raycast method in Table 7, it can also be seen that the difference between the average values for the hiragana task and the hiragana + alphanumeric task is smaller than the difference for the hiragana + kanji task. Regarding standard deviation, the standard method displays the smallest and the raycast method displays the largest for each task and overall.