In an experiment with 15 lottery balls, researchers painted 11 of the balls red and asked study participants which ball they would bet on. Participants overwhelmingly chose the painted balls – even though each ball had an equal likelihood of winning. This is known as Category Size Bias.
This bias causes us to believe that an option classified into a large category is superior to an option classified into a smaller category. In addition, we tend to believe that options within large categories “take no” on the characteristics of the category itself. In reality, neither belief is rooted in fact.
When providing options to your customers, use category sizes to direct their attention to the products you would like to sell most. Avoid using too many categories (this will lead to Choice Overwhelm) and choose your categories based on criteria that are relevant to your brand or product type (for example, if you are selling baseball bats, organize them by size or material rather than color).