Impact of Different Pairings of Respondents on Scores on the Supports Intensity Scale-Adult Version (SIS-A).

Hagiwara et al. (2021) asked 1,000 Japanese adults with intellectual disability to complete the SIS-A. Each adult also picked two to four people who knew them well. The team then mixed and matched these respondents to see how the final support-need score changed.

They tested 14 different respondent pairs. Some groups had only family. Others added a teacher or paid staff. One group included the adult with ID alongside family and staff.

Three or more people in the room pushed the score up. Groups with only two raters gave the lowest numbers. When the adult with ID joined the group, the total score dropped. The dip was biggest when the adult sat beside one professional or one family member.

In short, more voices meant higher reported needs. Adding the person's own voice pulled the number back down.

Kuppens et al. (2010) had already shown the SIS six-factor structure is solid. Mayumi now tells us the structure stays solid but the raw number moves with who you ask.

Sisson et al. (1993) saw the same rater split in depression screens. Caregivers rated more symptoms; self-raters reported fewer. Mayumi finds the same pattern on support needs twenty-eight years later.

Matson et al. (2004) showed teacher scales beat parent scales for kids with ID. Mayumi extends this to adults: paid staff, not family, drive the higher SIS-A scores once you have three or more people.

Before you write a support plan, check who filled out the SIS-A. If the team had only two people, the score may under-count needs. If the adult with ID was a respondent, add a small buffer before you decide on hours. Aim for at least three raters and balance family with paid staff. This keeps your plan honest and your funding request consistent.