Data-Driven Usability Assessment Model for Smartphones: A Causal Analytic Approach

Usability is an emerging subject for smartphone design and service, which results in the overall quality and achievement of a product and allows users to perform various tasks. In this context, this study aims to propose an integrated smartphone usability framework for higher service level and user experience with a causal analytic approach. Involving tested relationships with theoretical concerns a conceptual usability assessment model is proposed including design, customer focus, quality, innovation, usability, and user perception variables. The provided model is developed using the Bayesian neural networks based universal structure modeling (USM) method. The reliability and validity are empirically tested for the questionnaire data collected from 1068 smartphone users. The results and findings showed that design, customer focus, quality, and innovation explain usability, and user perception as an ultimate variable is interpreted by usability. Also, strategic, and valuable information for smartphone designers and marketing people to understand user perceptions for smartphone usability is provided.

Smartphone addiction and its association with upper body musculoskeletal symptoms among university students classified by age and gender

[Purpose] The purposes of this study were to: 1) survey smartphone addiction among university students, 2) survey the prevalence of upper body musculoskeletal symptoms in relation to the respondents’ sitting posture, and 3) determine the association between smartphone addiction and upper body musculoskeletal symptoms, classified by age and gender. [Participants and Methods] Two self-report questionnaires were employed to collect data from 2,645 university students in Chiang Mai, Thailand. [Results] Of 2,027 respondents (860 males and 1,167 females), the participants’ ages ranged from 18 to 26 years with a mean age of 20.5 ± 1.38 years. The prevalence of smartphone addiction and upper body musculoskeletal symptoms among participants were 15.9% and 30%, respectively. Overall, the mean value of pain severity was 3.66 ± 1.67 out of 10 on the visual analog scale. Multivariate logistic regression analysis revealed that smartphone addiction (OR=6.05, 95% CI: 4.68–7.84), was significantly associated with upper-body musculoskeletal symptoms when adjusted by age and gender. [Conclusion] The prevalence of upper body musculoskeletal symptoms was relatively high, especially for female smartphone users and students aged over 20 years. These results suggest that smartphone addiction may be a potential risk factor for upper body musculoskeletal symptoms in university students.

Musculoskeletal pain and risk factors associated with smartphone use in university students

Background:

Smartphone has become a very popular necessity among students. An individual has to look at their phone's small monitor and perform repetitive movements in an awkward posture for a prolonged duration.

Objectives:

To assess the prevalence of musculoskeletal pain and associated risk factors in university students because of smartphone usage.

Subjects and Methods:

A cross-sectional study was conducted with 2000 university students using a semi-structured questionnaire comprising demographic profile, smartphone usage characteristics, presence of musculoskeletal pain, and specific area of pain according to the body region.

Results:

Among the 2000 students, 44.05% reported musculoskeletal pain. The most common sites of pain were the neck (34.2%), thumb (17.45%), lower back (16.7%), and elbow (16.6%). There was an association between prevalence of musculoskeletal pain with the size of the smartphone (P = 0.005), the predominant purpose of smartphone usage (P = 0.002), position preferred while using smartphone (P = 0.000), and the level at which smartphone is held during usage (P = 0.05). Logistic regression analysis revealed that the strongest predictor of musculoskeletal pain was the size of the smartphone.

Conclusion:

The study reported that the prevalence of pain in smartphone users is high with common sites being neck, thumb, and lower back region. Also, the size of the smartphone had a significant association with musculoskeletal pain.

Effect of neck flexion angles on neck muscle activity among smartphone users with and without neck pain

This study examined the differences in neck muscle activity at various neck flexion angles in smartphone users with and without neck pain. Forty-four participants performed texting tasks for 1 min and 30 s. Neck muscle activity and pain in the neck were measured at different neck flexion angles. There was a difference in neck muscle activity for each of the neck flexion angles; the Cervical Erector Spinae (CES) muscle activity increased while the Upper Trapezius (UT) muscle activity decreased when at increased neck flexion angles. At neck flexion angle of 0°-15°, the activity of both CES and UT muscles were acceptably low. Smartphone users with neck pain had slightly higher muscle activity levels than smartphone users without neck pain. In conclusion, smartphone users should consider adopting neck flexion angles between 0 and 15 degrees during smartphone use as there is an association between this neck flexion angle range and reduced CES muscle activity. Practitioner summary: This study demonstrated that both smartphone users with and without neck pain should try to keep their neck flexion angle between 0° and 15° when using their smartphone. This would reduce neck muscle activity and the risk of developing neck disorders associated with smartphone use.

Ergonomic risk assessment of smartphone users using the Rapid Upper Limb Assessment (RULA) tool

The number of smartphone users globally is rapidly increasing. This study aimed to assess the level of ergonomic risk to smartphone users, and to evaluate the correlation between any self-reported musculoskeletal disorders and the level of ergonomic risk. Thirty participants completed a questionnaire, tailored specifically for smartphone users, to determine any musculoskeletal disorders. Participants were given a seated smartphone texting task and their postures were video recorded during the task. The video scenarios were evaluated by three independent researchers to determine the level of ergonomic risk using the Rapid Upper Limb Assessment (RULA) tool. RULA is an observation-based screening tool which has been widely used to assess the postural risk of IT device users. However, it has not yet been specifically utilized with smartphone users. The RULA tool scores identified ergonomics risks from using smartphones to text. Most smartphone users had a total RULA Grand Score of 6 for both sides (left side: 80.00%, right side: 90.00%), indicating the need for further investigation and changes (Action Level 3). Notably, no participants had acceptable RULA Grand Scores of 1 or 2. The correlation between musculoskeletal disorders and the ergonomic risk among smartphone users was determined using the Chi-Square test and Fisher's exact test; p<0.05 was considered statistically significant. There was a significant correlation between right RULA Grand Score and neck musculoskeletal disorder (χ2 = 9.424 at p value = 0.009) and right RULA Grand Score and upper back musculoskeletal disorder (χ2 = 31.717 at p value <0.001). RULA Score B (combination of neck, trunk and leg postures) and RULA Score D (combination of Score B, muscle use and force scores for group B) were also significantly correlated with neck musculoskeletal disorders (χ2 = 19.286 at p value<0.001 and χ2 = 9.310 at p value = 0.002 respectively). The RULA results identified the high ergonomics risk of smartphone users, this resulted from two key risk factors: posture and muscle use. The neck, trunk and leg postures had a combined effect on neck musculoskeletal disorders. Future investigations should consider these factors when designing ergonomic interventions for smartphone users.

The relationship between smartphone use and subjective musculoskeletal symptoms and university students

[Purpose] The purpose of this study was to investigate the use of smartphones by university students in selected areas, their musculoskeletal symptoms, and the associated hazard ratio. [Subjects and Methods] This involved the completion of a self-administered questionnaire by dental hygiene students in Seoul, Gyeonggido, and Gyeongsangbukdo. The 292 completed copies of the questionnaire were then analyzed. [Results] The most painful body regions after the use of smartphones were found to be the shoulders and neck. In the musculoskeletal system, back pain was found to have a positive correlation with the size of the smartphone’s liquid crystal display (LCD) screen, and pain in legs and feet were found to have a negative correlation with the length of time that the smartphone was used. As a result, it was revealed that the use of a smartphone was correlated with musculoskeletal symptoms. [Conclusion] Therefore, in today’s environment, where the use of smartphones is on the rise, it is necessary to improve the ways that they are used and to develop a preventive program to alleviate the symptoms of musculoskeletal damage.