Hi,
am not quite sure about this, but you might need to go back to the original Berg articles.

1) K O Berg, S L Wood-Dauphine, JI Williams, D ed Gayton (1989) Measuring balance in the elderly: preliminary development of an instrument. Physiotherapy Canada, 41 (6): 304-311

2) K O Berg, S L Wood-Dauphine, JI Williams, B E Maki (1992) Measuring balance in the elderly: validation of an instrument. Canadian J of Pub Health, 83 suppl. 7-11

3) K O Berg, B E Maki, S L Wood-Dauphine, JI Williams, P J Holliday (1992) Clinical and laboratory measures of postural balance in an elderly population. Arch Phys Med Rehab; 73: 1073-1080

Regards,
Fyzzio