As mentioned in the discussion of our results, performance time was statistically significant using the T9 method of input. Therefore, our hypothesis that performance times would improve using the T9 input was confirmed. Some instances of user satisfaction were statistically significant using T9 but some were not. User ratings were significantly higher for overall experience, likelihood of purchasing phone and more likely to use for T9. However, frustration level was also statistically higher using T9 and time to master T9 versus standard input was not statistically significant. Therefore, our results for user satisfaction does not support our hypothesis that users will be more satisfied with the T9 input method. Although users said they are more likely to purchase a phone with T9 and were encouraged to use it after the experiment, they were also more frustrated with it. This is important when considering the performance time versus frustration trade-off. Longer learning/training time led to user frustration. Users rated their overall experience higher using T9 because it got the job done quicker once they were trained, but the training itself led many users to become frustrated. Another factor that contributed to the frustration is that all the users already knew how to use the 12-key keypad but had to carefully read the instructions and learn how to use T9. Most people prefer things that are familiar to them even if it leads to better performance times.

We did show a statistically significant difference in performance times between the T9 and the 12-key keypad method of input. If the outlier data is removed, then we can also show a statistically significant difference in user satisfaction for the two types of input. This result is reflected in an alternate refined theory.

Refine the theory

Since our results only confirm part of our hypothesis. Users are able to perform faster using T9 input. However, unfamiliarity with the technology and the need for training leads to frustration. Therefore we can refine the theory as follows. For text input on cellular phones, users perform better using T9. Given longer and better training and practice sessions, user satisfaction will also be statistically significant using T9.

Suggestions for future researchers

A primary consideration for future researches is the performance time versus frustration trade-off. To decrease frustration among users, researchers could give them better training sessions explaining in detail how to use the T9 method. We gave the users five minutes of time to practice. However, due to the newness and unfamiliarity of the technology, the time given to practice was probably not enough. In the future, users could be given longer time to practice and get acquainted with using T9 since they already know how to use the 12-key keypad. Since all the users were already familiar with using 12-key keypad they were less frustrated with it. One way to deal with this issue is to pick users who are novices as opposed to intermediate and advanced users of standard input. In this way, they will be open to learning T9 and report less frustration. Another possibility would be to train the users before the experiment on how to use T9 so they come into the experiment already familiar with both methods of input. Then, we cannot measure not only performance time but also user satisfaction on fairer grounds.

A further suggestion would be to increase the number of subjects used. Although, we used thirty subjects, using even more subjects would give more accurate results and the outlying data would have less of an effect. The subject group could also be made more homogenous to represent the pubic more completely since most of our subjects were people in our classes or people we knew. Since cellular phone users encompass all ages, subjects should be taken from various age groups. Most of our subjects were in their early adulthood since they were mostly students. Having subjects from various occupations, and different age groups would therefore remove the possibility of skewed results.

Impact for practitioners

Since the T9 input method had a statistically significant difference in its performance time for data entry in cellular phones, designers might want to examine what it is about T9 which leads to higher performance times. The main difference in T9 versus the 12-key keypad is the number of keystrokes. The 12-key keypad requires several keystrokes just to type in a single letter. Since the T9 only requires one keystroke per letter and uses a built in algorithm to look at combinations of letters, it reduces performance time significantly. This suggests that designers should work on reducing the number of keystrokes per entry and develop algorithms similar to T9, which could be even faster or more efficient. Even though it frustrated users, they still said that they are more likely to purchase the phone, which uses T9 on the survey and were more satisfied with their overall experience with it. One improvement in the T9 is to perhaps have an interactive training session on the cellular phone, which familiarizes users with the technology. This could once again be because users felt like they were saving time with reducing the number of keystrokes and because the cellular phone actually had a built-in dictionary of its own for predicting words. Designers should therefore note, that in this fast-paced world, time is everything. Although, the technology might require longer and more extensive training, if it saves time and increases performance in the long run, users are more likely to be satisfied with it and to therefore, buy it. In the performance time versus frustration level trade-off, designers should realize that with time being an important factor, users will in the end, prefer technology that is faster and more efficient regardless of frustration in the beginning.