Validity and Judgment Bias in Visual Analysis of Single-Case Data

Validity and Judgment Bias in Visual Analysis of Single-Case Data

Authors

  • Jürgen Wilbert
  • Jannis Bosch
  • Timo Lüke

Keywords:

Single-case research, visual analysis, judgment, trend, curriculum-based measure- ment, reliability, validity

Abstract

Analysis of data from single-case intervention studies commonly involves visual analysis. Previous research indicates that visual analysis may suffer from low reliability and unprom- ising error rates. We investigated the reliability and validity of visual analysis and explored to what extent data trends affect judgments. We administered a within-subject experiment in which 186 teacher-education students visually analyzed specifically constructed single-case graphs that included either an intervention effect, a trend effect, both effects, or no effect. Participants identified intervention effects in 75% of the graphs, regardless of the existence of a trend. Type I error rates were low (5%) in graphs without a trend but increased fivefold (25%) for graphs with a trend. Inter- and intra-rater reliability was low, particularly when a trend was present in the data.

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Published

2023-05-31

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