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Testing Of Document Holder

  Testing Organization And Objective

A comparative quantitative analysis to determine the differences in muscle load, posture and individual preferences of the Heavy Duty Document Holder and a traditional (horizontal to the monitor) document holder. Testing was conducted by Dr. Wanda Smith, CEO of Global Ergonomic Technologies, Palo Alto, California. Dr. Smith is one of two Americans on the International ISO ergonomic standards committee, currently sits on multiple ANSI committees, and has been involved with ergonomic studies for over 27 years.


The experimental protocol used in this evaluation was based on usability testing specified in the International Organization for Standardization (ISO) Ergonomic Standard 9241. The standard specifies test subjects, stimuli, experimental design, environmental conditions, furniture features and adjustments, data collection procedures, data analysis recommendations, and performance metrics. The standard requires a test subject sample representative of the intended user population. Since the evaluation summarized in this report was a pilot test, it included a small sample. The ISO task used in this study is thatspecified in ISO 9241 Part 4 for keyboards.


Significant differences were analyzed using multivariable analysis of variances. Rating differences were analyzed using the Kruskel-Wallis analysis of variance and median tests.

  I. Muscle Load

Average load for the muscles controlling head rotation was significantly different between document holders. The average muscle load for the traditional document holder was almost three times higher than the average muscle load for Heavy Duty Document Holder. Across the 28 EMG sessions, muscle load due to head rotation with the Vu Ryte document holder averaged 10 microvolts, significantly less than the average of 30 microvolts for the traditional product.

  Ii. Posture

The average head/posture rotation for the Heavy Duty Document Holder was significantly less than the average rotation for the traditional document holder. NOTE: The head postures exhibited with the traditional document holder were not within acceptable ranges of the proposed ISO requirement. However, the postures demonstrated with the Heavy Duty Document Holder were within the acceptable ranges of the ISO standard. The average positive tilt was not significantly different between the document holders.

  Iii. Preferences

Subject preferences of features of both products did result in statistically significant differences. The Heavy Duty Document Holder was statistically significantly rated as superior for: a. neck comfort b. visual comfort c. overall comfort d. preference for use on job The Heavy Duty Document Holder was also preferred for: a. number of features b. customization to fit user's needs c. ease of viewing d. visibility of text e. appearance f. impression of productivity The preference differences between the two document holders after subjects had used both were significant.



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