Difficulty Rating Scale

Danford, Gary Scot, PhD
Project title: 
Rehabilitation Engineering Research Center on Universal Design and the Built Environment at Buffalo - Buildings in Use
Project Number: 
Tool type: 
Tool class: 
Nonengineering tool
Disability targeted: 
All disabilities
Study target: 
People with and without disabilities performing tasks
Study purpose or goal: 
To gauge the difficulty of use based on subjective ratings.
Who administers this tool?: 
Research assistants observing people with and without physical impairments performing tasks in an environment.
Ease of use: 
Very easy
Time to complete: 
>1 minute per item
Equipment required: 
Rating cards
Are any approvals required?: 
How is it administered?: 
Researchers ask whether a task was easy, difficult, or in-between. Then they present the participant with a 7 point rating scale (-3 to +3). Fewer points mean better reliability. This made it easier for respondents. Researchers can create more points to improve sensitivity.
What is the scope or what areas does it cover?: 
RERC researchers created a bipolar scale: i.e. difficult to easy is negative to positive.
Development background: 
The scale is an adaptation of a previously developed scale. (Published by Pitrella and Kappler. Research Institute on Human Engineering. Pitrella, F.D. & Kappler, W. (1988). Identification and evaluation of scale design principles in the development of the Extend Range Sequential Judgment Scale. Wachtberg, Germany: Research Institute for Human Engineering.)
Development methodology: 
The original measure had a 15-point unipolar scale to elicit participants’ subjective responses to human engineering factors. The original measure ask for a determination on a 15 point unipolar scale in 2 steps: users are first asked to judge a task positive or negative or in-between, then asked for a subjective rating based on the 15 points.
Has sensitivity and specificity been tested?: 
The tool has been tested and validated.
Can this tool be used for other purposes/populations?: 
The scale could be uses for product testing. It was used to test lab benches for a manufacturer. The scale is primarily applicable to environment or task. It has been used several times since then in universal design projects, in functional measures for wheelchair anthropometrics in combination with computer measures, and in design of universal bathroom where it was used in focus groups.
Sample type: 
Males with and without disabilities; women with disabilities using a model kitchen; men and women with varying disabilities utilizing the features of existing buildings.
Data analysis: 
Is complete
The first validation of the scale used a hand-gripped pinch mechanism set at different strengths. When a female researcher administered the scale, the participants (males) reported higher ease of use than the pincher recorded.
The tool has been tested and validated. It has been used in several projects, including the first year of the Buildings in Use Project. It utilizes descriptive statistics. The scale was used to assess participants subjective reactions to the usability of the universal design features of a building. Subjective reactions were strong in talking about how much more accessible the Lighthouse building (in New York) was compared to others. The Lighthouse building was designed with UD in mind. Results were compared to function performance measure and a strong correspondence was found. One study found the usability rating scale depends upon previous experience. A study used the scale with full-scale model kitchens that were fully compliant versus “impossible.” Women with mobility impairments were brought in to use the kitchen. Even the difficult kitchen was reported “easy to use”. Follow up at home discovered kitchens at home were just as bad.","
Research methods: 
Descriptive statistics
Peer review status: 
Who uses the collected data?: 
The data gathered has been used in universal design projects. It can be used by architects, designers, advocates, policy makers, and consumers, among others.
Is this tool available free of charge?: 
Danise Levine