Development of the Difficulty with Mobility Questionnaire: A Pilot Study

Publications

Share / Export Citation / Email / Print / Text size:

Vision Rehabilitation International

Guide Dogs NSW/ACT

Subject: Health Care Sciences & Services, Medicine, Rehabilitation

GET ALERTS

eISSN: 2652-3647

DESCRIPTION

227
Reader(s)
406
Visit(s)
0
Comment(s)
0
Share(s)

SEARCH WITHIN CONTENT

FIND ARTICLE

Volume / Issue / page

Archive
Volume 12 (2021)
Volume 11 (2020)
Volume 10 (2019)
Volume 9 (2017-2018)
Volume 8 (2016)
Volume 7 (2015)
Volume 6 (2013-2014)
Volume 5 (2012)
Volume 4 (2011)
Volume 3 (2010)
Volume 2 (2009)
Volume 1 (2008)
Related articles

VOLUME 6 , ISSUE 1 (April 2013-2014) > List of articles

Development of the Difficulty with Mobility Questionnaire: A Pilot Study

Steven J. La Grow, Ed.D. * / Bashir Ebrahim, OAM, Grad. Dip. Rehab. Studies * / Andy Towers, Ph.D. *

Citation Information : International Journal of Orientation & Mobility. Volume 6, Issue 1, Pages 59-69, DOI: https://doi.org/10.21307/ijom-2013-007

License : (CC-BY-NC-ND-4.0)

Published Online: 16-April-2018

ARTICLE

ABSTRACT

A 23-item difficulty with mobility questionnaire (DMQ) was piloted with 32 persons who had participated in a one-week orientation and mobility (O&M) course offered by Guide Dogs Queensland in early 2014 to determine its potential utility as an outcome measure for O&M instruction. The DMQ was assessed for reliability, validity, and sensitivity. Reliability was established using Cronbach’s alpha coefficient. Validity was assessed by determining the extent to which the total difficulty score correlated with a single-item global measure of ability to get around. Sensitivity of each of the difficulty items to reflect change following completion of the course was assessed by comparing pretreatment to post-treatment scores using paired samples t-tests. Acceptable levels of reliability, validity, and sensitivity were demonstrated.

 

Graphical ABSTRACT

Experiencing new-found difficulty with the performance of various tasks required for getting around built environments is one of the most common and disabling consequences of the onset of a significant vision impairment (Brouwer, Sadlo, Winding, & Hanneman, 2010; Long, Boyette, & Griffin-Shirley, 1996). These tasks include, but are not limited to (1) avoiding obstacles in one’s path of travel, (2) walking along streets with footpaths, (3) walking along streets without footpaths, (4) crossing quiet streets, (5) crossing busy streets with pedestrian control devices, (6) crossing busy streets without pedestrian control devices, (7) identifying drop-offs (curbs/steps), (8) negotiating curbs, (9) negotiating stairs, (10) getting around in one’s home and garden, (11) getting around in one’s immediate neighborhood, (12) getting around in office buildings/schools/ hospital, (13) getting around in department stores, (14) getting around in supermarkets, (15) getting around in shopping malls, (16) negotiating parking lots, (17) travelling on elevators, (18) travelling on escalators, (19) maintaining orientation during travel, (20) re-establishing orientation if lost, (21) travelling in familiar outdoor environments, (22) travelling in unfamiliar outdoor environments and (23) using public transportation (Barlow, Bentzen, Sauerburger, & Franck, 2010; Brouwer, Sadlo, Winding, & Hanneman, 2008; Deverell, Taylor, & Prentice, 2009; Hill & Ponder, 1976; Jacobson, 2013; La Grow & Blasch, 1992; La Grow & Long, 2011; Long, McNeal, & Griffin-Shirley, 1990; Long, Reiser, & Hill, 1990; Smith, De l’Aune, & Geruschat, 1992; Yablonski, 2000).

Orientation and mobility (O&M) instruction is designed to restore one’s ability to get around built environments through the use of a range of adaptive aids, techniques and strategies; each of which are designed to reduce the difficulty posed by one or more of the 23 tasks listed above (Deverell, Taylor, & Prentice, 2009; Hill & Ponder, 1976; Jacobson, 2013; La Grow & Long, 2011). The effectiveness of these aids, techniques, and strategies have been evaluated in a number of ways over the years, including the use of measures of efficiency, time, safety, effectiveness for avoiding or contacting objects and drop-offs in one’s path of travel, success in locating travel objectives, satisfaction with travel, satisfaction with independence and ease and frequency of travel (Bentzen & Barlow, 1995; Blades, Lippa, Gooedge, Jacobson, & Kitchin, 2002; Dodds, Carter, & Howarth, 1983; Dodds, Clark-Carter, & Howarth, 1984; Geruschat & De l’Aune, 1989; Havik, Kooijman, & Steyvers, 2011; Kaila, Legge, Roy, & Ogale, 2010; Kim, Wall Emerson, & Curtis, 2009; Kim, Wall Emerson, & Curtis, 2010; McKinley, Goldfarb, & Goodrich, 1994; La Grow, 1999; Tellevik, Martinsen, Storlilokken, & Elmerskog, 2000). While each of these measures have proved to be effective in assessing some component of O&M instruction none are sufficient to serve as an outcome measure of O&M instruction as a whole. An outcome measure must be inclusive enough to reflect the overall purpose for which the service, program or intervention is delivered (Whiteneck, 1994). As a result, the author’s propose the development of a battery which will assess individual perception of difficulty with performing each of the 23 mobility related tasks listed above. It is expected that different aspects of O&M instruction will result in decreased levels of difficulty on one or more of these tasks with the most comprehensive programs affecting all of the 23 items included. The authors have tentatively named this measure the Difficulty with Mobility Questionnaire (DMQ). The purpose of this study was to pilot the DMQ with a group of people receiving O&M instruction to determine its utility as an outcome measure by assessing its reliability, validity, and sensitivity.

Methodology

All persons presenting for one of two one-week residential O&M instruction programs (long cane 1 and long cane 2) in January and February of 2014 at Guide Dogs Queensland (GDQ) were asked to rate the level of difficulty that each of the 23 items included in the DMQ posed to them before and after participating in their O&M training program. They were also asked to rate their ability to get around on both occasions. This was done as part of the GDQ’s standard intake and discharge process. This project has been evaluated for ethical concerns by peer review, judged to be low risk and recorded on Massey University’s Human Ethics Committee Low Risk Database. Consequently, it has not been reviewed by one of the University’s Human Ethics Committees. The authors are responsible for the ethical conduct of this research. If there are any concerns about the conduct of this research that you wish to raise with someone other than the authors, please contact Professor John O’Neill, Director (Research Ethics), telephone +64 6 350 5249, e-mail humanethics@massey.ac.nz.

Participants

Thirty-two persons presented for O&M instruction during this time period. They ranged in age from 20 to 82 (mean age = 53.9) and 40% were male. All met the Guide Dogs Queensland criteria that a person is eligible to receive rehabilitation services from GDQ when: The person has a vision loss that is permanent or likely to be permanent (i.e., irreversible, chronic, is not responsive to intervention measures, not corrected by spectacles); AND the vision loss results in a substantial reduction of the person’s capacity to be safely and independently mobile (Eligibility for Rehabilitation Services Policy: Guide Dogs Queensland). In response to the question ‘How much usable vision would you say you have?’ 4 persons (12%) reported having none, 25 (79%) a little and 3 (9%) a lot.

Measures

The DMQ consisted of 23 items identified as either a hindrance to non-visual travel or as a point of intervention for O&M training in a review of O&M related literature (Barlow, Bentzen, Sauerburger, & Franck, 2010; Brouwer, Sadlo, Winding, & Hanneman, 2008; Deverell, Taylor, & Prentice, 2009; Hill & Ponder, 1976; La Grow & Blasch, 1992; La Grow & Long, 2011; Jacobson, 2013; Long, McNeal, & Griffin-Shirley, 1990; Long, Reiser, & Hill, 1990; Smith, De l’Aune, & Geruschat, 1992; Yablonski, 2000). The 23 difficulty items were presented following the root question ‘How much difficulty would you say you have in completing the following tasks?’ and available responses ranged from 1 ‘none at all’ to 5 ‘an extreme amount’. The possibility to reply ‘not applicable’ was also made available for the instances when an individual genuinely had no opportunity to perform a given task (i.e., using public transportation). Table 1 illustrates the format and response options for the 23 DMQ items.

Table 1.

The Difficulty with Mobility Questionnaire (DMQ) item format and response options.

10.21307_ijom-2013-007-tbl1.jpg

In addition, a single-item measure of ability to get around (AGA) was administered both pre and post intervention. This measure was drawn from the World Health Organization Qualify of Life BREF (WHO, 1996). The question posed was ‘How well are you able to get around?’ with available responses ranging from 1 ‘Very poorly’ to 5 ‘Very well’. The use of this item as a global measure of mobility is well established (La Grow, Alpass, Stephens, & Towers, 2011; La Grow, Yeung, Towers, Alpass, & Stephens, 2011, 2013; Yeung, La Grow, Towers, Alpass, & Stephens, 2011). The AGA score was administered as a means to assess the concurrent validity of the DMQ.

Analysis

The DMQ was assessed for reliability, validity, and sensitivity. Reliability, a measure of consistency, is a necessary but not sufficient condition to establish the validity of a measure. Reliability of the DMQ was assessed using Cronbach’s alpha coefficient, a commonly used measure of internal consistency (Pallant, 2011). Cronhach’s alpha coefficient should be above 0.7 for the measure to be considered reliable (DeVellis, 2003). Validity reflects the degree to which an item or a battery of items appear to measure what they are supposed to measure (i.e., in this case a reduction in difficulty with independent travel gained by participating in an O&M program for blind and vision impaired persons). Two measures of validity were used in this study; face validity (the degree to which the measure looks like it is measuring what is supposed to be measuring) and concurrent validity (the extent to which scores on the measure of interest correlate with scores on a measure of a related construct). Face validity of the measure was evaluated by presenting each of the 23 DMQ items and the single measure of AGA to three different focus groups for evaluation; clients currently undergoing an O&M program at GDQ (n=3), clients who had completed an O&M program at GDQ in the last 5 years (N=5), and O&M instructors employed by GDQ (N = 4). The groups met separately and were asked to focus on each of the 23 separate items of the DMQ, the root question and the response category available in DMQ, as well as, the separate AGA item. They were specifically asked if each of the DMQ items were relevant to their mobility, if the root question asking them to rate the difficulty of the task was a reasonable way to address these tasks, if they felt any item should be excluded or if other items should be included and whether they thought the AGA item was reflective of overall mobility. Concurrent validity of the DMQ was assessed in this study by determining the extent to which the total score for the DMQ (i.e., the sum of the separate difficulty items) and the scores for each of the separate difficulty items correlated with the AGA score.

The evaluation of reliability and concurrent validity was conducted using pretest scores only. The measure of sensitivity was conducted using both pre and post-test scores.

Sensitivity of each of the 23 difficulty items, the total mean difficulty score and the single AGA score were assessed to determine if they would reflect change following O&M instruction (in this case a one-week residential O&M program). This was done by comparing pretreatment to post-treatment scores using paired samples t-tests.

Results

Reliability

Chronbach’s Alpha for the 23 item DMQ measure was found to be 0.962. As can be seen in Table 2, the removal of only one difficulty item (i.e., travelling on lifts) would have resulted in an increased alpha, but this change would not have been statistically or pragmatically meaningful (i.e., a change in alpha from 0.962 to 0963).

Table 2.

Cronbach’s alpha for the DMQ as a whole and Cronbach’s alpha if each of the 23 DMQ items were deleted from the measure.

10.21307_ijom-2013-007-tbl2.jpg

Validity

The face validity of the measure appeared to be strong. All of the three focus groups felt that the DMQ items were relevant to their mobility. They were all happy with the root question asking them to rate the difficulty of the task thinking it was a reasonable way to address these tasks. They identified no items which they felt should be excluded nor did they identify additional items to add to the battery. They all thought the AGA item was reflective of overall mobility and a reasonable question to assess the battery against. They did suggest some minor wording changes to 2 of the DMQ items (i.e., change ‘avoiding obstacles in your path of travel’ to ‘negotiating obstacles in your path of travel’ and ‘getting around in shopping malls’ to ‘getting around in shopping precincts’).

The concurrent validity of this measure appeared to be satisfactory. As can be seen in Table 3, the relationship between the pre-training scores for the total score obtained from the DMQ and AGM was found to be strong (r = 0.735). Furthermore, the strength of the relationship found between the scores of 9 of the individual difficulty items and AGM were found to be strong (i.e., r =0.5 to 1.0), 13 were found to be medium (r = 0.3 to .49) and 1 was weak (0.1 to .29).

Table 3.

Correlation with each of the 23 difficulty items and the mean total score with AGM.

10.21307_ijom-2013-007-tbl3.jpg

Sensitivity

Sensitivity of the DMQ was assessed by comparing pre-treatment to post-treatment scores to determine if significant differences were obtained from time 1 to time 2. As can be seen in Table 4, a change in the desired direction (i.e., a decrease in difficulty) was observed in all 23 difficulty items following the completion of a week-long O&M program, with the change in all but 3 of those (i.e., crossing busy streets with pedestrian control devices, getting around department stores and using public transportation) found to be statistically significantly (i.e., < 0.05). In addition, the change in the total difficulty score (i.e., the mean sum of all difficulty scores) was significant (t = 14.33, p < 0.001); decreasing from a mean of 2.18 (SD = 0.88) at pre-test to a mean of 1.88 (SD = 0.41) at post-test. Similarly, the mean score for AGA was found to significantly increase (t = 6.78, p < 0.001) from a pre-test mean of 3.34 (SD = 0.94) to a post-test mean of 4.38 (SD = 0.49).

Table 4.

Pre and post test scores for ability to get around, total mean difficulty score and each of the 23 separate difficulty items.

10.21307_ijom-2013-007-tbl4.jpg

Discussion

The DMQ has been proposed as an O&M outcome measure. This measure is viewed as a constellation of loosely related items which have been identified as being the focus of various aspects of O&M instruction and, therefore, may be expected to be positively impacted by the provision of a comprehensive O&M program. The results of this study provide an initial indication that the DMQ, as currently constructed, has sufficient reliability, validity, and sensitivity to justify its use as an outcome measure for O&M instruction. The Cronbach’s alpha found for this measure indicates that the internal consistency is high for both the measure as a whole and for each of the items included in the battery. The removal of only one item (travelling on lifts) would have resulted in little meaningful increase in the overall alpha of the measure, the removal of two others (negotiating stairs and travelling in familiar outdoor environments) would have no effect on overall alpha, and the removal of any of the rest would have lowered it. The response of the three focal groups indicated that the DMQ appeared to be measuring what they thought should be measured in relation to their individual O&M and that the AGM score did seem to be a reasonable measure to compare it to. The total mean score for the DMQ was strongly related to the AGM reflecting good concurrent validity. Finally, the DMQ appears to be reasonably sensitive to change occurring as a result of O&M instruction. The mean total DMQ score and the scores from 20 of the 23 individual difficulty items were found to be significantly different following the completion of a one-week residential O&M program (either Long Cane 1 or 2). It is important to note that these programs (i.e., Long Cane 1 and 2) were discrete parts of an overall O&M program of instruction which may consist of on-going domiciliary instruction (i.e., home-based instruction), Long Cane 1 and Long Cane 2, night lessons, public transport lessons, and other programs of varying length provided to teach the use of various electronic travel and orientation aids. As a result, the intervention used here to determine the sensitivity of this measure should in no way be thought of as representing a full O&M program nor should the change in scores seen here be thought of as reflecting the quantum of change that may occur from before having an instruction to that obtained following the completion of a comprehensive O&M program.

There are a number of limitations to this study which need to be highlighted. First, the study was conducted with just 32 participants; many more will be needed before further and full psychometric assessment of the DMQ can be carried out. Second, the intervention used was not illustrative of a full mobility program, but rather just a small part of one. Third, no control groups were used to ensure that the change observed in the scores from pre to post were in fact due to the provision of the intervention and not simply the result of the passage of time or a placebo effect.

The DMQ is intended to provide O&M programs with a targeted indicator of the effectiveness of instruction on clients’ ability to move around their environments, while providing the capacity to assess which individual aspects of mobility (e.g., avoiding obstacles in your path of travel, identifying drop-offs) that specific programs of instructions more effectively target (e.g., basic or advanced long cane instruction). Further data collection is currently being undertaken with Guide Dogs Queensland on a larger sample that has completed a full program of instruction in order to assess that the DMQ is an adequate outcome measure for O&M instruction. With this expanded dataset we also aim to assess whether various DMQ items will cluster around a number of discrete constructs and thus underpin the development of brief DMQ versions for O&M program use.

References


  1. Barlow, J. M., Bentzen, B. L., Sauerburger, D., & Franck, L. (2010). Teaching travel at complex intersections. In Wiener W. R., Welsh R. L. & Blasch B. B. (Eds.), Foundations of orientation and mobility: Volume II, Instructional strategies and practical applications (pp. 352-419). New York: American Foundation for the Blind.
  2. Bentzen, B., & Barlow, J. (1995). Impact of curb ramps on the safety of persons who are blind. Journal of Visual Impairment & Blindness, 89, 319-328.
  3. Blades, M., Lippa, Y., Golledge, R., Jacobson, R. D., & Kitchin, R. (2002). The effect of spatial tasks on visually impa ired peoples’ wayfinding abilities. Journal of Visual Impairment & Blindness, 96, 407-420.
    [CROSSREF]
  4. Brouwer, D. M., Sadlo, G., Winding, K., & Hanneman, M. I. G. (2008). Limitations in mobility: Experiences of visually impaired older people. British Journal of Occupational Therapy, 71, 414-421.
    [CROSSREF]
  5. DeVellis, R. (2003). Scale development: Theory and applications (2nd Ed.). Thousand Oaks, CA. Sage.
  6. Deverell, L., Taylor, S., & Prentice, J. (2009). Orientation and mobility methods: Techniques for independent travel. Kew, Vic: Guide Dogs Victoria.
  7. Havik, E., Kooijman, A., & Steyvers, F. (2011). The effectiveness of verbal information provided by electronic travel aids for visually impaired persons. Journal of Visual Impairment & Blindness, 105, 624-637.
    [CROSSREF]
  8. Hill, E., & Ponder, P. (1976). Orientation and mobility techniques: A guide for the practitioner. New York: American Foundation for the Blind.
  9. Jacobson, W. (2013). The art and science of teaching orientation and mobility to persons with visual impairments, (2nd Ed). New York: American Foundation for the Blind.
  10. Kalia, A. A., Legge, G. E., Roy, R., & Ogale, A. (2010). Assessment of indoor route-finding technology for people with visual impairment. Journal of Visual Impairment & Blindness, 104, 135–147.
    [PUBMED] [CROSSREF]
  11. Kim, D. S., Wall Emerson, R., & Curtis, A. (2009). Drop-off detection with the long cane: Effects of different cane techniques on performance. Journal of Visual Impairment & Blindness, 103, 519-530.
    [PUBMED] [CROSSREF]
  12. Kim, D. S., Wall Emerson, R., & Curtis, A. (2010). Interaction effects of the amount of practice, preferred cane technique, and type of cane technique used on drop-off detection performance. Journal of Visual Impairment & Blindness, 104, 453-463.
    [PUBMED] [CROSSREF]
  13. La Grow, S., Alpass, F., Stephens, C., & Towers, A. (2011). Factors affecting perceived quality of life of older persons with self-reported visual disability. Quality of Life Research, 20, 407-413.
    [CROSSREF]
  14. La Grow, S., & Blasch, B. (1992). Orientation and mobility services for older persons. In Orr A. L. (Ed.), Vision and aging: Crossroads for service delivery (pp. 255-287). New York: American Foundation for the Blind.
  15. La Grow, S., & Long, R. (2011). Orientation and mobility: Techniques for independence, (2nd, Ed.). Revised and expanded. Alexandria, VA. The Association for the Education and Rehabilitation of the Blind and Visually Impaired.
  16. La Grow, S., Yeung, P., Towers, A., Alpass, F., & Stephens, C. (2011). Determinants of overall quality of life among older persons who have difficulty seeing: The importance of the ability to get around. Journal of Visual Impairment & Blindness, 105, 7209-730.
  17. La Grow, S., Yeung, P., Towers, A., Alpass, F., & Stephens, C. (2013). The impact of mobility on quality of life among older persons. Journal of Aging and Health, 25, 723-736.
    [CROSSREF]
  18. Long, R. G., Boyette, L.W., & Griffin-Shirley, N. (1996). Older persons and community travel: The effect of visual impairment. Journal of Visual Impairment & Blindness, 90, 302-313.
  19. Long, R., McNeal, L., & Griffin-Shirley, N. J (1990). The effect of visual loss on mobility of elderly persons, Final Report. National Institute on Disability and Rehabilitation Research Grant No. 133 GH 70038.
  20. Long, R., Rieser, J., & Hill, E. (1990). Mobility in individuals with moderate visual impairments. Journal of Visual Impairment & Blindness, 84, 111-118.
  21. Pallant, J. (2011). SPSS survival manual: A step by step guide to data analysis using SPSS (4th Ed.). Crows Nest, NSW, Australia: Allen & Unwin.
  22. Smith, A., De l’Aune, W., & Geruschat, D. (1992). Low vision mobility: Perceptions of orientation and mobility specialists and persons with low vision. Journal of Visual Impairment & Blindness, 86, 58-62.
  23. Tellevik, J. M., Martinsen, H., Storlilokken, M., & Elmerskog, B. (2000). Development and evaluation of a procedure to assess mobility route learning. Journal of Visual Impairment & Blindness, 94, 197-204.
    [CROSSREF]
  24. Whiteneck, G. G. (1994). Measuring what matters: Key rehabilitation outcomes. Archives of Physical Medical Rehabilitation, 75, 1073-1076.
    [CROSSREF]
  25. WHO. (1996). WHOQOL-BREF: Introduction, administration, scoring and generic version of the assessment. Geneva: Program on mental health, World Health Organization.
  26. Yablonski, M. S. (2000). Functional orientation and mobility. In Silverstone B., Lang M. A., Rosenthal B. P. & Faye E. E. (Eds.), The Lighthouse handbook on vision impairment and vision rehabilitation (pp. 855-868). Oxford: Oxford University Press.
  27. Yeung, P., La Grow, S., Towers, A., Alpass, F., & Stephens, C. (2011). The centrality of O&M in rehabilitation programs designed to enhance quality of life: A structural equation modelling analysis. International Journal of Orientation & Mobility, 4, 10-20.
    [CROSSREF]
XML PDF Share

FIGURES & TABLES

Table 1.

The Difficulty with Mobility Questionnaire (DMQ) item format and response options.

Full Size   |   Slide (.pptx)

Table 2.

Cronbach’s alpha for the DMQ as a whole and Cronbach’s alpha if each of the 23 DMQ items were deleted from the measure.

Full Size   |   Slide (.pptx)

Table 3.

Correlation with each of the 23 difficulty items and the mean total score with AGM.

Full Size   |   Slide (.pptx)

Table 4.

Pre and post test scores for ability to get around, total mean difficulty score and each of the 23 separate difficulty items.

Full Size   |   Slide (.pptx)

REFERENCES

  1. Barlow, J. M., Bentzen, B. L., Sauerburger, D., & Franck, L. (2010). Teaching travel at complex intersections. In Wiener W. R., Welsh R. L. & Blasch B. B. (Eds.), Foundations of orientation and mobility: Volume II, Instructional strategies and practical applications (pp. 352-419). New York: American Foundation for the Blind.
  2. Bentzen, B., & Barlow, J. (1995). Impact of curb ramps on the safety of persons who are blind. Journal of Visual Impairment & Blindness, 89, 319-328.
  3. Blades, M., Lippa, Y., Golledge, R., Jacobson, R. D., & Kitchin, R. (2002). The effect of spatial tasks on visually impa ired peoples’ wayfinding abilities. Journal of Visual Impairment & Blindness, 96, 407-420.
    [CROSSREF]
  4. Brouwer, D. M., Sadlo, G., Winding, K., & Hanneman, M. I. G. (2008). Limitations in mobility: Experiences of visually impaired older people. British Journal of Occupational Therapy, 71, 414-421.
    [CROSSREF]
  5. DeVellis, R. (2003). Scale development: Theory and applications (2nd Ed.). Thousand Oaks, CA. Sage.
  6. Deverell, L., Taylor, S., & Prentice, J. (2009). Orientation and mobility methods: Techniques for independent travel. Kew, Vic: Guide Dogs Victoria.
  7. Havik, E., Kooijman, A., & Steyvers, F. (2011). The effectiveness of verbal information provided by electronic travel aids for visually impaired persons. Journal of Visual Impairment & Blindness, 105, 624-637.
    [CROSSREF]
  8. Hill, E., & Ponder, P. (1976). Orientation and mobility techniques: A guide for the practitioner. New York: American Foundation for the Blind.
  9. Jacobson, W. (2013). The art and science of teaching orientation and mobility to persons with visual impairments, (2nd Ed). New York: American Foundation for the Blind.
  10. Kalia, A. A., Legge, G. E., Roy, R., & Ogale, A. (2010). Assessment of indoor route-finding technology for people with visual impairment. Journal of Visual Impairment & Blindness, 104, 135–147.
    [PUBMED] [CROSSREF]
  11. Kim, D. S., Wall Emerson, R., & Curtis, A. (2009). Drop-off detection with the long cane: Effects of different cane techniques on performance. Journal of Visual Impairment & Blindness, 103, 519-530.
    [PUBMED] [CROSSREF]
  12. Kim, D. S., Wall Emerson, R., & Curtis, A. (2010). Interaction effects of the amount of practice, preferred cane technique, and type of cane technique used on drop-off detection performance. Journal of Visual Impairment & Blindness, 104, 453-463.
    [PUBMED] [CROSSREF]
  13. La Grow, S., Alpass, F., Stephens, C., & Towers, A. (2011). Factors affecting perceived quality of life of older persons with self-reported visual disability. Quality of Life Research, 20, 407-413.
    [CROSSREF]
  14. La Grow, S., & Blasch, B. (1992). Orientation and mobility services for older persons. In Orr A. L. (Ed.), Vision and aging: Crossroads for service delivery (pp. 255-287). New York: American Foundation for the Blind.
  15. La Grow, S., & Long, R. (2011). Orientation and mobility: Techniques for independence, (2nd, Ed.). Revised and expanded. Alexandria, VA. The Association for the Education and Rehabilitation of the Blind and Visually Impaired.
  16. La Grow, S., Yeung, P., Towers, A., Alpass, F., & Stephens, C. (2011). Determinants of overall quality of life among older persons who have difficulty seeing: The importance of the ability to get around. Journal of Visual Impairment & Blindness, 105, 7209-730.
  17. La Grow, S., Yeung, P., Towers, A., Alpass, F., & Stephens, C. (2013). The impact of mobility on quality of life among older persons. Journal of Aging and Health, 25, 723-736.
    [CROSSREF]
  18. Long, R. G., Boyette, L.W., & Griffin-Shirley, N. (1996). Older persons and community travel: The effect of visual impairment. Journal of Visual Impairment & Blindness, 90, 302-313.
  19. Long, R., McNeal, L., & Griffin-Shirley, N. J (1990). The effect of visual loss on mobility of elderly persons, Final Report. National Institute on Disability and Rehabilitation Research Grant No. 133 GH 70038.
  20. Long, R., Rieser, J., & Hill, E. (1990). Mobility in individuals with moderate visual impairments. Journal of Visual Impairment & Blindness, 84, 111-118.
  21. Pallant, J. (2011). SPSS survival manual: A step by step guide to data analysis using SPSS (4th Ed.). Crows Nest, NSW, Australia: Allen & Unwin.
  22. Smith, A., De l’Aune, W., & Geruschat, D. (1992). Low vision mobility: Perceptions of orientation and mobility specialists and persons with low vision. Journal of Visual Impairment & Blindness, 86, 58-62.
  23. Tellevik, J. M., Martinsen, H., Storlilokken, M., & Elmerskog, B. (2000). Development and evaluation of a procedure to assess mobility route learning. Journal of Visual Impairment & Blindness, 94, 197-204.
    [CROSSREF]
  24. Whiteneck, G. G. (1994). Measuring what matters: Key rehabilitation outcomes. Archives of Physical Medical Rehabilitation, 75, 1073-1076.
    [CROSSREF]
  25. WHO. (1996). WHOQOL-BREF: Introduction, administration, scoring and generic version of the assessment. Geneva: Program on mental health, World Health Organization.
  26. Yablonski, M. S. (2000). Functional orientation and mobility. In Silverstone B., Lang M. A., Rosenthal B. P. & Faye E. E. (Eds.), The Lighthouse handbook on vision impairment and vision rehabilitation (pp. 855-868). Oxford: Oxford University Press.
  27. Yeung, P., La Grow, S., Towers, A., Alpass, F., & Stephens, C. (2011). The centrality of O&M in rehabilitation programs designed to enhance quality of life: A structural equation modelling analysis. International Journal of Orientation & Mobility, 4, 10-20.
    [CROSSREF]

EXTRA FILES

COMMENTS