Klusowski, J. Small, D.A., &, Goldenberg, J. Even Number Prevalence in Quantity Decisions. Manuscript in preparation.


People choose even numbers more frequently than odd numbers when selecting quantities across a variety of contexts (e.g., units of a product to acquire or consume). This tendency manifests in both archival shopping data and online survey data. It also largely extends beyond the previously known tendency for people to choose multiples of ten. Importantly, this tendency attenuates when the relative fluency of odd quantities increases, suggesting implications for better understanding and influencing quantity decisions.


​All study materials, data, and code are available upon request, except the Kilts-Nielsen Consumer Panel Data that are available via Kilts Center for Marketing--if you have not used their system before, happy to help you reproduce our analyses.

Klusowski, J., Small, D.A., & Simmons, J.P. (2021). Does choice cause an illusion of control? Psychological Science , 32(2), 159-172.


Previous research suggests that choice causes an illusion of control—that it makes people feel more likely to achieve preferable outcomes, even when they are selecting among options that are functionally identical (e.g., lottery tickets with an identical chance of winning). This research has been widely accepted as evidence that choice can have significant welfare effects, even when it confers no actual control.


​In this article, we report the results of 17 experiments (N = 10,825 online/laboratory participants) examining whether choice truly causes an illusion of control. We find that choice rarely makes people feel more likely to achieve preferable outcomes—unless it makes the preferable outcomes actually more likely—and when it does, it is not because choice causes an illusion, but because choice reflects some participants’ pre-existing (illusory) beliefs that the functionally identical options are not identical.


All study materials, data, and code are available at the following link: https://osf.io/g2cbe/.