TY - JOUR
T1 - The development of the de morton mobility index (DEMMI) in an older acute medical population
T2 - item reduction using the Rasch model (part 1)
AU - de Morton, Natalie A
AU - Davidson, Megan
AU - Keating, Jennifer Lyn
PY - 2013
Y1 - 2013
N2 - The DEMMI (de Morton Mobility Index) is a new and advanced instrument for measuring the mobility of all older
adults across clinical settings. It overcomes practical and clinimetric limitations of existing mobility instruments.
This study reports the process of item reduction using the Rasch model in the development of the DEMMI. Prior
to this study, qualitative methods were employed to generate a pool of 51 items for potential inclusion in the
DEMMI. The aim of this study was to reduce the item set to a unidimensional subset of items that ranged across
the mobility spectrum from bed bound to high levels of independent mobility. Fifty-one physical performance
mobility items were tested in a sample of older acute medical patients. A total of 215 mobility assessments were
performed. Seventeen mobility items that spanned the mobility spectrum were selected for inclusion in the new
instrument. The 17 item scale fitted the Rasch model. Items operated consistently across the mobility spectrum
regardless of patient age, gender, cognition, primary language or time of administration during hospitalisation.
Using the Rasch model, an interval level scoring system was developed with a score range of 0 to 100.
AB - The DEMMI (de Morton Mobility Index) is a new and advanced instrument for measuring the mobility of all older
adults across clinical settings. It overcomes practical and clinimetric limitations of existing mobility instruments.
This study reports the process of item reduction using the Rasch model in the development of the DEMMI. Prior
to this study, qualitative methods were employed to generate a pool of 51 items for potential inclusion in the
DEMMI. The aim of this study was to reduce the item set to a unidimensional subset of items that ranged across
the mobility spectrum from bed bound to high levels of independent mobility. Fifty-one physical performance
mobility items were tested in a sample of older acute medical patients. A total of 215 mobility assessments were
performed. Seventeen mobility items that spanned the mobility spectrum were selected for inclusion in the new
instrument. The 17 item scale fitted the Rasch model. Items operated consistently across the mobility spectrum
regardless of patient age, gender, cognition, primary language or time of administration during hospitalisation.
Using the Rasch model, an interval level scoring system was developed with a score range of 0 to 100.
M3 - Article
C2 - 23816594
SN - 1529-7713
VL - 14
SP - 159
EP - 178
JO - Journal of Applied Measurement
JF - Journal of Applied Measurement
IS - 2
ER -