Recommendations on Standards for the Design of Medical Diagnostic Equipment for Adults with Disabilities, Advisory Committee Final Report

1. Abdomen depth (AD)

Abdomen depth was analyzed as the overall clearance depth beneath the mammography machine, and measured from the anterior-most aspect of the abdomen to the anterior-most aspect of the occupied wheelchair (e.g., to the footrest or toe-tip). The data were analyzed using both, univariate and multivariate methods.

Univariate analysis
The univariate analysis examines AD alone and is appropriate when no other clearance dimension is constrained or bounded (e.g., knee clearance height, foot clearance height or depth). Table 1 and Figure 1 show the percentiles and maximum observed values for male and female wheelchair users. Within device type, female users had slightly less AD compared to male users. The 95th percentile value for female users of manual and power wheelchairs was approximately 30.5 in. and would accommodate about 95% of female users assuming no other clearance dimensions is restricted or bounded. Based on the current study sample, accommodating the entire user population would require a clearance depth between 33 in. – 37 in.

Table 1: Percentile and maximum values for Abdomen Depth (in.) obtained from univariate analyses

Figure 1: Boxplot showing the distribution for abdomen depth (inches) across wheelchair type and occupant gender. The dotted line (30.5 in) depicts the 95th percentile value for female wheelchair users, both manual and power.

Note on Multivariate Analysis

The above univariate analysis is only applicable in the case of one critical dimension (i.e., abdomen to anterior-most point depth) and all other knee clearance dimensions are unrestricted or unbounded. If more than one dimension is bounded (e.g., combinations of knee clearance height or depth, foot clearance height or depth, occupied width, etc.) then a multivariate analysis which involves simultaneous consideration of multiple dimensions is more appropriate for performing clearance assessments. As the number of dimensions in the multivariate analysis increases it is possible that the resulting space requirements are larger in comparison to the univariate case where each dimension is analyzed separately.