Reliability, Construct Validity and Completeness of the "Winterthur Observation Protocol" Applied to Early...

To assess intra- and inter-rater reliability, construct validity and completeness of the "Winterthur Observation Protocol" (WOP).

Intra-rater and inter-rater reliability were calculated with the interclass correlation coefficient (ICC) with 95% confidence intervals and Cohens's kappa coefficient based on 18 5-min sequences from six video-recorded early intervention sessions rated by two assessors. Construct validity was based on an increase of coaching over time (three video-recorded sessions) in six therapists during a course on coaching techniques. WOP's completeness - the capacity to cover at least 95% of the specific coaching strategies - was assessed based on 18 video-recorded sessions.

Intra-rater reliability was excellent: ICCs of continuous variables varied from .87 to 1.0; the kappa-value of categorical variables was 0.90. Inter-rater reliability was sufficient to excellent: ICCs of continuous variables were .47-1.0; the kappa-value of categorical variables was .89, indicating excellent intra-rater reliability. Increasing application of coaching behavior during the course provided evidence of construct validity. More than 95% of the specific coaching strategies could be scored with the WOP.

The WOP is a promising instrument to quantify the contents of early intervention approaches in pediatric physical therapy using coaching. Results must be interpreted with caution due to limited generalizability.