Introduction: This study aims to conduct the first evaluation of measurement properties in
the scale of balance recovery confidence. There are several measurement properties such as
unidimensionality, validity (to what extent does the instrument measure the construct it
purports to measure) and reliability (the degree to which measurement is free from error) of
the PROM that is needed to be studied.
This psychometric validation aims to provide evidence that the PROM can be purposefully used
in practice, given that rigorous methods have been applied for the development and validation
of the BRC. For the study, balance recovery confidence is defined as the perceived ability to
recover one's balance from perturbations, such as a slip, a trip, or a loss of balance that
can occur in common, everyday activities. This focus will leave little ambiguity about
precisely what is being measured. The resulting questionnaire is intended to be approximately
20 questions and should not take longer than 10 min to complete. The instrument is not
intended to be used as a diagnostic tool of impaired specific balance recovery mechanisms.
The BRC allows clinicians and researchers to quantifiably determine the balance recovery
confidence in older adults and use the scale as a conduit for understanding older people's
perspectives when encountering different perturbations during their daily activities.
The objectives are to:
To evaluate the measurement properties of the BRC, i.e. acceptability, targeting,
scaling assumptions and reliability using Classical Test Theory (CTT), the internal
scale structure using Rasch measurement theory in the Singapore community-dwelling older
adults.
To assess the construct validity of the refined BRC against commonly used PROMs and
performance measures in the Singapore community-dwelling older adults.
To refine the items, response categories, and scale structure of the BRC using Rasch
measurement theory in an English-speaking sample of community-dwelling older adults in
Singapore.
Methods: Participants will attend two sessions in the study. In the first session, the
researcher will use a measurement data form to record the participants' results of four
questionnaires: BRC, ABC, FES-I, LLFDI-F and three performance measures: Jamar hand strength
dynamometer, 30-second chair stand test and Mini BESTest. After seven days, participants will
attend the second session to complete the BRC, and the GPE scale which will be used to ensure
participants' perception of their abilities remained unchanged during the seven days. The
time interval of 7-day had been reported to be sufficient to minimise recall bias.
Participants will be asked if they have had experienced a fall, near-fall, or encountered any
incident that might affect their balance recovery ability over the past seven days.
Statistical analysis: Quantitative data will be analysed and interpreted through two
measurement test theories using IBM SPSS Statistic V.26.0 and Winsteps V.4.5.0. Classical
test theory is a traditional quantitative approach to test the validity and reliability of a
scale based on its items. This approach is based on the assumption that every observed score
is a function of an individual's true score and random error. In contrast, RA works on the
probability of a person's level on an item is a function of the person's ability and of the
difficulty of the item. RA evaluates a scale against a mathematical measurement model and
analyses the scale at the level of each item, and each person. Measurement properties
including unidimensionality, internal structure, validity and reliability will be evaluated.
