Measuring parent strategy use in early intervention: Reliability and validity of the Naturalistic Developmental Behavioral Intervention Fidelity Rating Scale across strategy types.
Bailey J Sone, Aaron J Kaat, Megan Y Roberts
PMID 34030519WHAT IT FOUND
The NDBI-Fi scale reliably measures parent fidelity after intervention, matching gold-standard micro-coding.
It is less accurate at baseline for responsive strategies and has poor item-level reliability, so use it for progress monitoring, not for analyzing specific teaching techniques.
Key findings
01The NDBI-Fi demonstrated good interrater reliability for overall, responsive, and directive composite scores, with alpha values between 0.704 and 0.774.
02Post-intervention, the NDBI-Fi showed strong convergence with micro-coded measures across all composite scores (r = 0.57 to 0.63), but baseline correlation for responsive strategies was weaker (r = 0.30).
03Item-level reliability was inconsistent, with five of nine items falling below the minimum acceptable standard, including one item with poor reliability (α = 0.389).
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
Raters were not blind to timepoint (baseline vs. post-intervention) for most videos, which could have influenced sensitivity analyses. No standardized video viewing protocol was used, which may have contributed to inconsistent item-level reliability. The study did not include community members or parents in the development or evaluation process. Item-level reliability was poor for several items, limiting the tool's utility for analyzing specific intervention components.
Declared interests
The study was supported by the National Institutes of Health (R01DC014709). The authors declared no other conflicts of interest.
The easy way to misread this
Do not use the NDBI-Fi to measure baseline parent responsiveness or to evaluate individual strategy items. The scale's reliability at baseline for responsive strategies was weak, and item-level reliability was inconsistent, meaning it cannot accurately pinpoint which specific techniques a parent is using before or during early stages of intervention.