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Experts' Misinterpretation of Box Plots - a Dual Processing Approach.
Stephanie Lem1, Patrick Onghena2, Lieven Verschaffel1
1Centre for Instructional Psychology and Technology, KU Leuven, Belgium.
Psychologica Belgica
|November 28, 2018
Summary
Even statistical experts misinterpret box plots, mistaking area for frequency instead of density. This heuristic reasoning suggests box plots may be an ineffective data visualization, questioning their curriculum inclusion.
Area of Science:
- Data visualization
- Statistical graphics
- Cognitive psychology
Background:
- Box plots are widely used in statistics education and data reporting.
- Previous research indicates students frequently misinterpret the box area as frequency or proportion, not density.
- This misinterpretation is linked to visual saliency and heuristic reasoning.
Purpose of the Study:
- To investigate if expert box plot users exhibit similar misinterpretations as students.
- To determine if experts also show signs of heuristic reasoning in box plot interpretation.
- To evaluate the effectiveness of box plots as a data representation tool.
Main Methods:
- A reaction time test was employed to assess interpretation accuracy and speed.
- Expert users of box plots were recruited for the study.
- Participants' responses were analyzed for signs of heuristic reasoning.
Main Results:
- Evidence of heuristic reasoning was found in expert users.
- Both accuracy and reaction times indicated flawed interpretation processes in experts.
- The findings suggest experts are not immune to common box plot misinterpretations.
Conclusions:
- Expert users of box plots demonstrate heuristic reasoning, similar to students.
- The study questions the suitability and pedagogical value of box plots for data representation.
- Reconsideration of box plots' prominent role in statistics education is warranted.