Date of Award

12-2021

Degree Name

Doctor of Philosophy

Department

Interdisciplinary Health Sciences

First Advisor

Dr. Robert Wall Emerson

Second Advisor

Dr. Linda Shuster

Third Advisor

Dr. William Wiener

Fourth Advisor

Dr. Kieran Fogarty

Keywords

Orientation and mobility, blindness, validity, low vision, assessment, visual impairments

Abstract

Orientation and mobility specialists for young children who are blind or visually impaired have relied on informal assessments or commercially available tools designed for sighted children to track developmental progress. When Bradley-Johnson (1994) literally wrote the book on assessment in blindness, the sharing and refinement of common tools led to professionals working in teams to sift and winnow the checklists, and move the best available tools into wider circulation. This has led to the evolution of the practitioner made tools becoming the published tools, although they have not yet had statistical evidence to support their efficacy. This three-paper dissertation aims to move assessment development forward in the field of blind rehabilitation by exploring the reliability and validity of a widely used assessment instrument and demonstrating a repeatable process for assessment development and refinement that is appropriate for use with the heterogeneous population of people with blindness and visual impairment.

As a concrete application of the test development process, this three-paper dissertation explores whether the Birth to 6 Orientation and Mobility Skills Inventory – Research Edition (B6OMSI-RE) demonstrates sufficient reliability and validity measures for high-stakes assessment. Research begins with a Delphi study to codify the professional wisdom in the field. The first paper uses this structure of repeated interviews of experts to establish consensus on the items to include in assessment. Next, reliability is established, so that multiple sources can contribute data meaningfully to the test development process with such a low incidence population. The second paper examines reliability measures from the Classical Test Theory framework and informs revisions to the standardized administration and scoring of items. Finally, test development uses real field data and the Item Response Theory framework to scale items, grouping together those that measure the same latent trait, and ordering them with relation to their demonstrated difficulty. The third paper uses Mokken scaling to establish the construct validity of the mobility subscale.

While exploring the parametric characteristics of the B6OMSI-RE, this dissertation demonstrates several ways that an assessment tool can be taken through a research-based process for test development. It shows that trained orientation and mobility specialists can consistently and reliably administer the test after a one-hour training and establishes reliability and validity of the B6OMSI-RE assessment tool, that allows for a test of early-intervention O&M skills that can be used for intervention decisions and progress monitoring for children from birth to six years of age.

Access Setting

Dissertation-Open Access

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