Friday, July 15, 2011


Order matters. Whether it is the order on a ballot. The order of choices in a survey, or the order of options on a menu.
“Very small but cumulated decreases in food intake may be sufficient to have significant effects, even erasing obesity over a period of years” (Rozin et al., 2011). In two studies, one a lab study and the other a real-world study, we examine the effect of manipulating the position of different foods on a restaurant menu. Items placed at the beginning or the end of the list of their category options were up to twice as popular as when they were placed in the center of the list. Given this effect, placing healthier menu items at the top or bottom of item lists and less healthy ones in their center (e.g., sugared drinks vs. calorie-free drinks) should result in some increase in favor of healthier food choices. [Judgment and Decision Making, Vol. 6, No. 4, June 2011, pp. 333–342]
In the case of voting:

And so it is with voting. Candidates listed first on the ballot get about two percentage points more votes on average than they would have if they had been listed later (flipping a 49 to 51 defeat into a 51 to 49 victory). In fact, in about half the races I have studied, the advantage of first place is even bigger — certainly big enough to win some elections these days.

Order bias in surveys can stem from the order of the questions in the survey or the order of the answer choice within a question. For example early questions can prejudice the answers to later questions through a priming effect. In the context of categorical answers provided, if they are inherently unordered, their order might affect respondents choice over them.

Modern software allows you to randomize both if you anticipate a large problem.

There is also an order bias when it comes to evaluating people, be it for a job or a contest. I imagine this will be tested with American Idol data at some point. But it is better to be first or last, not in the middle.

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