Bergkvist, Lars I. and Rossiter, John R., 2008, The role of ad likability in predicting an ad's campaign performance, Journal of Advertising, 37(2), 85-97.
The Advertising Research Foundation's (ARF's) influential Copy Research Validity Project (CRVP) endorsed ad likability, Lad, as the single best copy-test predictor of campaign sales results, and Lad scores are now widely used by practitioners to approve or reject ads for campaigns. The CRVP's findings are based on a between-groups experimental design and are incapable of proving whether Lad causes purchase, because individuals who like the ad could be different individuals from those who purchase the product. The present study is an individual-level, quasi-experimental test in which four ads for new brands of different products were copy tested and then "tracked" in simulated campaigns and posttested on brand-based communication effects. The CRVP's favorable findings for ad likability were not confirmed in these individual-level tests. For each of the four ads, Lad in the copy test significantly predicted brand attitude (Ab) in the copy test, but failed to predict campaign-induced Ab in the posttest.