Reliability analysis of the Motivation Assessment Scale: a failure to replicate.
The Motivation Assessment Scale gives unreliable answers across raters, so treat its results as a rough guess, not a verdict.
01Research in Context
What this study did
The authors asked two staff members to fill out the Motivation Assessment Scale for the same adults with intellectual disability. They wanted to see if both raters picked the same reason for each problem behavior.
Pairs came from both a school and a state facility. No extra training was given beyond the one-page MAS instructions.
What they found
Agreement was poor. Only 16 of 55 pairs agreed on the single function that kept the behavior alive. No item reached 80% match across raters.
In plain words, the scale gave different answers depending on who filled it out.
How this fits with other research
Rojahn et al. (1994) ran almost the same check three years later and got the same grim numbers for adults with severe ID who showed aggression. Together the two papers form a clean failure-to-replicate set: the MAS simply does not yield reliable ratings.
Chiviacowsky et al. (2013) widened the lens, pitting the MAS against the QABF in a head-to-head study. Both tools still failed at the item level, showing the 1991 verdict has not been fixed by later revisions.
Matson et al. (1999) offers a bright contrast. Their MESSIER scale, also used with adults who have severe ID, reached high interrater reliability. The difference shows the fault lies in the MAS itself, not in the rater pool or the population.
Why it matters
If two staff cannot agree on the function, the team may pick the wrong intervention. Treat a behavior as escape-maintained when it is really sensory, and you could put the client through useless demands. Use the MAS only as a conversation starter, never as the final word. Pair it with direct observation or a brief functional analysis, and train raters until they hit 90% agreement before you trust the data.
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02At a glance
03Original abstract
The Motivation Assessment Scale (MAS) has been proposed as an efficient questionnaire for identifying the source of reinforcement for an individual's self-injurious behavior (SIB). A previous reliability analysis of the MAS (Durand & Crimmins, 1988) reported interrater correlation coefficients ranging from .66 to .92, based on a comparison of responses provided by classroom teachers. In this study, the reliability of the MAS was reexamined with two independent groups of developmentally disabled individuals who exhibited SIB (N = 55). For the institutional sample (n = 39), the MAS was given to two staff members (a supervisor and therapy aide) who work with the individual daily. For the school sample (n = 16), the MAS was given to the teacher and teacher's aide who taught the student. The correlational analyses completed by Durand and Crimmins (1988) were repeated; in addition, a more precise analysis of interrater reliability was calculated based on the actual number of scoring agreements between the two raters. Results showed that only 16 of the 55 raters agreed on the category of reinforcement maintaining their client's or student's SIB, that only 15% of the correlation coefficients obtained were above .80, and that none of the reliability scores based on percent agreement between raters was above 80%.
Research in developmental disabilities, 1991 · doi:10.1016/0891-4222(91)90031-m