User Testing and Analysis

---

 4.1 Testing

The hanger prototype was created at a low-medium fidelity to evaluate the requirement that the modified hook must be easy to use. By constructing the hanger using planks of balsa wood, which were precisely cut and assembled to model the duck-shaped hook, the prototype was also able to simulate a greater mass for stabilization. This allowed for a meaningful preliminary analysis of the devised solution, as it ensured that the user’s experience wielding the product was not swayed by a significant weight discrepancy between the established prototype and ideal design. The hanger’s performance with respect to this requirement was assessed through user testing qualitatively by employing a user feedback form and Likert scale, and quantitatively by recording the time required for users to place the hanger on a clothing rod at four different angles. The tested requirement is summarized in the table below (see Table 1).

4.2 Testing Protocol

Prior to testing, a user feedback response survey was created on Google Forms. It was set so that responses were anonymous and included Likert scale-based questions asking users to respond to the following statements: “the modified hanger was easy to use” (see Fig. 4.), “I would use the modified hanger again,” and “I feel like I saved time using the modified hanger.” A five-point Likert scale was used, providing users with a total of six options: strongly agree, agree, neither agree nor disagree, disagree, strongly disagree, and not applicable (N/A). Limiting the number of options to six promoted meaningful responses from users. The neither agree nor disagree and N/A options were also critical to ensure that users were not pressured to select a random option that was unreflective of their preference if it was not represented in the provided options. Additionally, the form also asked users what angle of offset they felt was the easiest, with this being communicated as the angle causing the least resistance and being the most time-efficient. The form provided participants with four options (0°, 20°, 40°, and 60°); however, further iterations of user testing should include a neutral and N/A option for users who lack a strong preference.

Testing consisted of ten participants who each performed four distinct trials (of hanging the hanger on a standardized, round closet rod of 1.25 inches in diameter). Eight of the participants were classmates, while two were family members. The majority of the testing was conducted in a dorm setting, while the rest was conducted in a home setting. At the start of each trial, the user was instructed to stand two feet away from the closet rod, and hold the hanger in their dominant hand. The hanger, while still being held by the user, was then positioned at the test angle for the given trial number (0° for the first trial, 20° for the second trial, 40° for the third trial, and 60° for the fourth trial) using a protractor. It can be noted that at 0°, the hanger was parallel with the ground. Following the set up, the user was instructed to place the modified hanger hook on the closet rod. The user was also verbally and visually instructed that for trials two, three, and four where the hanger was to be hung on a rod at 20°, 40°, and 60° angles (respectively), that they were to maintain the angle while moving the hanger toward the rod. After the user confirmed they were ready, they were counted down from three. At zero, the mobile stopwatch was started and the user began to move their hand and the hanger towards the rod. When the contact between the user’s hand and the hanger was ceased, and the hanger had been fully placed on the rod, the stopwatch was stopped. The time it took the user to place the hanger on the rod was measured in seconds (to hundredths precision, which was chosen given the ± 0.01 s uncertainty for the digital stopwatch being used, on top of human error) for each attempt, and then recorded on Google Sheets for the purpose of data storage, analysis, and evaluation. Afterwards, the user was asked to complete the feedback form with predetermined questions.

4.3 Testing Data

Depicted above in Figure 4 and 5.

4.4 Interpretation of Testing

The testing results showed that a majority (sixty percent) of users strongly agreed that the hanger prototype created was easy to use, signifying that the design performed strongly with respect to the selected ease of use engineering requirement. Additionally, there was a small range of variance (the greatest being 0.29s) between the average time (s) required to hang the hanger from different angles. This demonstrates that the hanger is well adapted to a broad range of angles, which is beneficial to those with hand tremors, as it reduces the precision and fine-motor skills required to hang up the hanger, while not exceeding the 22 N of applied force. Based on this testing, there is no need for the hanger to be redesigned or revised regarding the chosen requirement. If the course allowed, different aspects of the design could be prototyped, such as a clamp/clip mechanism to secure the part of the hanger body that hinges up and down. A higher fidelity hanger could also be made with a thick metal to more closely simulate the duck shaped hook, rather than being constructed with balsa wood. A silicone-type grip along the sides of the hanger body could also be prototyped and tested to ensure clothes do not slide off the hanger. However, the small sample size of users must be heavily considered in the interpretation of the testing data. 

Testing consisted of ten participants, most of whom were classmates around 17-19 years of age. Additionally, the demographics (e.g. gender) and physical characteristics (e.g. height, weight, limb length) of the participants were not controlled. Overall, these factors play a role in the data and interpretation of the data, as the sample of users tested was not particularly reflective of the intended age range of the product, being midlife professionals. The lower ages and extraneous and varied physical qualities of those being tested may have easily skewed the observed times to hang the hanger from different angles, and/or exacerbated or lessened the differences between average times for the respective offset angles. In addition, a greater sample size and an increased quantity of testing data would increase the accuracy and precision of the data the team achieved from testing. 

With more time, the testing could also be arranged to be performed in a standardized location, as even a slight difference in the height of the closet rod could result in non-negligible discrepancies between the times recorded for the trials done in the dorm-setting and the home-setting. These discrepancies would be a result of the difference in distance between the hanger’s starting point and the closet rod two feet away (the diagonal/hypotenuse). Further, the participants were unaffected by intention tremors, meaning that differences between performance of the hanger for the target demographic of the product, and the testing users must be accounted for and expected. Testing could also be performed in a way that captures the speed of the test subjects as they hook the hanger onto the rod in attempts to reduce the margin of error that would result from timing (possibly by using velocity sensors available in the den). For the timing of the test subjects, error could also be minimized by using a more precise timer as opposed to a digital phone timer (a method extremely vulnerable to human error). 

Moreover, in future iterations of testing, one aspect of the protocol that could be revised is the wording of the Likert scale options. To avoid biased answers by test subjects, ideal questions would not lead test subjects to respond in a way they feel is “correct” or will provide the team with satisfaction. The current statement, “I would use the modified hanger again,” may have prompted the user to strongly agree to appease the design team, despite being an anonymous survey. The protocol would also benefit from the revision of allowing users to fill out the form in complete privacy, as during the current testing protocol, testers completed the form in the presence of the design team. This likely induced feelings of pressure among users and led them to answer in a way they felt would please the team. Furthermore, the protocol could have been modified to provide users with the opportunity to share written feedback on what they did not like about the hook if they answered negatively to any of the questions in the Likert scale survey.