2026 ASEE Annual Conference & Exposition

Variability is an unavoidable reality in manufacturing and engineering
design. However, as quantified through a scoping review of engineering
textbooks, "variability" is mentioned in <12% of books assigned to
engineering students through course reserve lists (Vo et
al. 2023). Alarmingly, some engineers have the tendency to "neglect"
variability---to make design decisions as though variability has no
meaningful consequences (del Rosario, 2024). It remains an open
question why and at what rate engineers tend to neglect variability.

Through a years-long mixed-methods project, we have developed a valid
and reliable survey instrument to measure decision-making behavior
under variability. This project started with initial qualitative work
to build a taxonomy of decision-making (del Rosario 2024), followed by
the development and deployment of a survey instrument to measure
behavior according to the taxonomy (del Rosario et al. 2025). In a
large (n=306) sample demographically representative of the
U.S. population, we found that the majority of U.S. adults (95% CI
[78%, 92%]) make sound choices with variability as their default
approach. This suggests that neglect of variability in engineering
runs counter to the cognitive resources that U.S. adults tend to
develop through natural learning.

In this short report, we will summarize findings from other studies
that suggest why variability is often neglected in engineering
practice, and what teaching practices can help combat this statistical
illiteracy.

Vo, K., A. Evans, S. Madan, and Z. del Rosario (2023). A Scoping
Review of Engineering Textbooks to Quantify the Teaching of
Uncertainty. In: ASEE Annual Conference and Exposition. eprint:
https://nemo.asee.org/public/conferences/327/papers/36798/view

del Rosario, Z. (2024a). Neglected, Acknowledged, or Targeted: A
Conceptual Framing of Variability, Data Analysis, and Domain
Consequences. Journal of Statistics and Data Science
Education. eprint: https://doi.org/10.1080/26939169.2024.2308119

del Rosario, Z., E. Saur, J. Ryu, J. Lin, and J. B. Wilmer
(2025). DECISIONS, VARIATION, AND VISUAL- IZATION: A NOVEL INSTRUMENT
FOR DECISION MAKING UNDER VARIABILITY. PsyArxiv. eprint:
https://doi.org/10.31234/osf.io/vujta_v1