Underdog Effect

What it is

The term belongs to opinion research, where it is usually paired with the bandwagon effect. Where the bandwagon effect describes movement toward the apparent majority, underdogging describes movement away from it. In economics the nearest relative is Harvey Leibenstein's snob effect (1950), in which demand for a commodity falls as others consume it because the buyer wants to be distinct from the crowd. The two are not the same. The snob effect concerns purchases and exclusivity, and underdogging concerns stated opinion and the side that appears to be losing.

In effect

A panel study of student groups' opinions on North American free trade (Cloutier, Nadeau and Guay, 1989, International Journal of Public Opinion Research) found that exposure to majority opinion trends produced both bandwagon and underdog effects. After controlling for non-causal factors, the authors attribute the effects partly to the stimuli and partly to people's efforts to keep their opinions internally consistent.

Nadeau and two co-authors (1993, International Political Science Review) built their test of the bandwagon effect on abortion and the constitutional future of Quebec around three methodological criteria for a valid test. One of the criteria was allowance for underdogging and for opinion shifts caused by factors outside the experiment. They report a bandwagon effect of roughly 5 to 7 per cent on both issues.

The practical consequence for design is that a study which records only movement toward the leader can overstate the bandwagon effect, because it leaves out the respondents who moved the other way.

What it does not say

It does not say that trailing sides generally gain from polls. The 1989 study reports that both movements occurred and explains them partly by the wish to keep opinions consistent, and the 1993 study allowed for underdogging in its design.

It does not have a size. Neither study reports a separate figure for the underdog effect, and no general estimate should be drawn from them.

It is not an established account of why people move. Nadeau and his co-authors say of the bandwagon effect that its reasons remain unclear, and the same caution applies here.

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