Finding functionality: Rasch analysis of the Functionality Appreciation Scale in community-dwelling adults in the US

Front. Rehabil. Sci., 2023 · DOI: 10.3389/fresc.2023.1222892 · Published: October 2, 2023

Simple Explanation

The Functionality Appreciation Scale (FAS) measures how much a person values what their body can do, regardless of any physical limits they might have. Rasch analysis was used to check if the FAS really measures one single concept (structural validity) and how well it does that in community-dwelling adults in the US. The study found that after some changes, the FAS mostly measures one thing well, but it might be too easy for the people tested, so it needs some harder questions.

Study Duration

June 2019 and September 2021

Participants

567 community-dwelling adults

Evidence Level

Not specified

Key Findings

1
After rescoring 3 items and deleting 1 item, the FAS had good person and item ﬁt (except item 4).
2
There was no DIF and only one item pair had LID (item 5–6).
3
However, there was a signiﬁcant ceiling effect (28.04%) and the person mean location was 3.06 ± 2.07 logits, indicating the FAS is too easy for community-dwelling adults in the US.

Research Summary

This study aimed to determine the structural validity of the FAS in community-dwelling adults in the US using Rasch Measurement Theory. The 6-item Rasch-based FAS demonstrated unidimensionality, good item ﬁt (except item 4) and person ﬁt, but the FAS will require more difﬁcult items to be added to improve the targeting of the scale, and better reliability. In conclusion, the 6-item Rasch-based FAS demonstrates good item ﬁt (except item 4) and person ﬁt, and unidimensionality through the paired t-test.

Practical Implications

Scale Refinement

More difficult items should be added to the FAS to reduce the ceiling effect and improve targeting for community-dwelling adults.

Clinical Application

Further Rasch analyses should be conducted in clinical populations to determine the FAS's validity and reliability in settings focused on prevention and treatment of negative body image.

Normative Data

The current results can serve as a normative sample to compare against clinical populations with body functionality appreciation problems.

Study Limitations

1
The sample lacks diversity.
2
The sample of community-dwelling participants included 14 adults with SCI and neuropathic pain.
3
One item still displays misﬁt (item 4) but removing it further decreased the reliability, so we decided to keep this item in.

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