Julie R. Irwin

Misleading Heuristics and Moderated Multiple Regression Models

Moderated multiple regression models allow the simple relationship between the dependent variable and an independent variable to depend on the level of another independent variable. The moderated relationship, often referred to as the interaction, is modeled by including a product term as an additional independent variable. Moderated relationships are central to marketing (e.g., Does the effect of promotion on sales depend on the market segment?). Multiple regression models not including a product term are widely used and well understood. The authors argue that researchers have derived from this simpler type of multiple regression several data analysis heuristics that, when inappropriately generalized to moderated multiple regression, can result in faulty interpretations of model coefficients and incorrect statistical analyses. Using theoretical arguments and constructed data sets, the authors describe these heuristics, discuss how they may easily be misapplied, and suggest some good practices for estimating, testing, and interpreting regression models that include moderated relationships.

Negative Consequences of Dichotomizing Continuous Predictor Variables

Marketing researchers frequently split (dichotomize) continuous predictor variables into two groups, as with a median split, before performing data analysis. The practice is prevalent, but its effects are not well understood. In this article, the authors present historical results on the effects of dichotomization of normal predictor variables rederived in a regression context that may be more relevant to marketing researchers. The authors then present new results on the effect of dichotomizing continuous predictor variables with various nonnormal distributions and examine the effects of dichotomization on model specification and fit in multiple regression. The authors conclude that dichotomization has only negative consequences and should be avoided.

Preference Reversals and the Measurement of Environmental Values

Numerous studies have demonstrated that theoretically equivalent measures of preference, such as choices and prices, can lead to systematically different preference orderings, known as preference reversals. Two major causes of preference reversals are the compatibility effect and the prominence effect. The present studies demonstrate that the combined effects of prominence and compatibility lead to predictable preference reversals in settings where improvements in air quality are compared with improvements in consumer commodities by two methods-willingness to pay for each improvement and choice (For which of the two improvements would you pay more? Which improvement is more valuable to you?). Willingness to pay leads to relatively greater preference for improved commodities; choice leads to relatively greater preference for improved air quality. These results extend the domain of preference reversals and pose a challenge to traditional theories of preference. At the applied level, these findings indicate the need to develop new methods for valuing environmental resources.

Willful ignorance in the request for product attribute information

Attribute information is not always readily available to consumers. This is especially true for ethical attributes, such as labor practices, environmental friendliness, and so forth. Intuitively, it might be expected that consumers who would use an attribute in their decision making should seek attribute information, especially if it is easily obtainable. In three studies, the authors measure discrepancies between requests for available ethical attribute information and actual use of the same attribute in a conjoint task. In both between-subjects and within-subjects designs, the authors show that consumers (1) underrequest ethical attribute information and (2) are especially likely to show request/use inconsistency if they care about the underlying ethical issue. Negative emotions, especially the avoidance of anger, appear to drive this willful ignorance. These results add to the growing literature on avoidance mechanisms and consumer decision making and may shed light on when ethical attributes do (and do not) play a role in actual purchase behavior.

Walking the Hedonic Product Treadmill: Default Contrast and Mood-Based Assimilation in Judgments of Predicted Happiness with a Target Product

Consumers often browse through many products (a product context) before evaluating a particular target product. We examine the influence of four product context characteristics on happiness with a target product: pleasantness, sequence, domain match with target (i.e., whether products in the context set belong to the same category as the target), and context set size. When context and target match, pleasant and improving (compared to less pleasant and worsening) contexts induce less happiness with the target product. When there is domain mismatch, however, the results are reversed. Furthermore, the assimilation effects are significantly influenced by set size, but the contrast effects are not. While the contrast effects appear to occur by default and appear to be driven by a process of comparison, the assimilation effects appear to be driven by mood. These effects hold even when perception of domain match is manipulated via instructional framing.

Ethical Decisions and Response Mode Compatibility: Weighting of Ethical Attributes in Consideration Sets Formed by Excluding versus Including Product Alternatives

Across four studies, including one involving an actual monetary decision, the authors demonstrate that forming a product consideration set by excluding versus including alternatives induces consumers to place more weight on ethical attributes, such as company labor practices and animal testing. This nonnormative difference reflects a compatibility between exclusion and ethics, and it holds regardless of attribute framing or consumer emotion. The authors also find that consumers judge others’ behavior more negatively for excluding ethical products than for including ethical products. These results have implications for the marketing of ethical products, both specifically (e.g., it is important to encourage exclusion modes) and generally (e.g., the failure to consider ethical products may reflect seemingly minor contextual issues guiding the decision process and not consumer disinterest in ethical issues).

Examining Medical Decision Making from a Marketing Perspective

This paper explores how consideration of the medical context can add newelements to marketing thought. Differences between the medical context andother consumer contexts are reviewed. The effects that the medical contexthas on the way traditional constructs such as involvement, affect andstress, uncertainty and satisfaction affect choice are discussed. Finally,emerging research in medical contexts where future discoveries could enhanceconsumer choice theory are presented.

Order Effects in Individual and Group Policy Allocations

Although citizen panels have become quite popular for policy making, there is very little research on how the procedures these groups employ to manage consensus affect their decision making. We measured the effect of a simple procedural mechanism, agenda order, on individual and group allocations for an HIV policy. Allocations made in a large-small (state-region-city) order were substantially smaller, overall, than were allocations made in small-large (city-region-state) order, and group allocations were smaller, overall, than were individual judgments. The Social Judgment Scheme model (Davis, 1996) provided a good fit of the group allocation, and suggested a mechanism for this overall downward shift in judgment. Normative (i.e. calibration) analyses, as well as subjective impressions (e.g. confidence, repeat judgments) favored relatively smaller allocations so that judgments made in large-small order, and judgments made in groups were arguably more defensible than were individual or small-large judgments. We discuss these strong agenda influences and their implications both for citizen panels and for theoretical research on group consensus.

Is more always better? Counter-intuitive effects in consumer assessment of environmental product attributes

The objective of this article is to study the influence of the number of environmental attributes of a product on the weight given to these attributes. The results of two experiments show that certified or uncertified environmental attributes on the same product are weighted less (more) by consumers when they are presented jointly (separately). This non-rational effect, called the embedding effect, is stronger for individuals deeply concerned with the environment and involved towards eco labels. The outcome of this study challenges the value of accumulating attributes when dealing with consumers of environmentally friendly products.

Toujours plus, toujours mieux ? Effet contre-intuitif de l'évaluation des attributs environnementaux du produit par le consommateur

L’objectif de cet article est d’étudier l’influence du nombre d’attributs environnementaux d’un produit de consommation sur le poids associé à ces attributs. Les résultats de deux expérimentations montrent que les consommateurs tendent à systématiquement sous-évaluer les attributs environnementaux (certifiés ou non) lorsqu’ils sont présentés ensemble, par rapport à une évaluation des mêmes attributs présentés séparément. Cet effet non rationnel, appelé effet d’inclusion, est plus fort pour les individus davantage préoccupés par l’environnement et impliqués envers les écolabels. Les conclusions de cette étude remettent en question l’intérêt de cumuler de tels attributs pour les consommateurs de produits pro-environnementaux.