Explaining context effects on choice using a model of comparative judgment

Context effects refer to the shifts in shares when another alternative is introduced in the choice set. The alternative can be asymmetrically dominated, asymmetrically dominating, totally dominated, or totally dominating. We developed a theoretically derived model based on the shifts in attribute valuation as a potential explanation for all context effects. First, the model is tested using data from previously published studies. As predicted, the results showed a high correlation between shifts in valuation and changes in the choice shares. The model is also tested using 2 studies that extend the design of the choice sets to include better alternatives in a search context and the removal of an alternative. The strong relation justifies the case for comparative valuation as an underlying mechanism for context effects. Assuming this valuation, the article illustrates how the framework can be used to develop new product strategies taking into account the values of the unchosen alternatives.