There’s an interesting article by Jonah Lehrer in the Dec. 13 issue of The New Yorker, “The Truth Wears Off:  Is there something wrong with the scientific method?” Lehrer reports that a growing number of scientists are concerned about what psychologist Joseph Banks Rhine termed the “decline effect.”  In a nutshell, the “decline effect” is an observed tendency for the size of an observed effect to decline over the course of studies attempting to replicate that effect.  Lehrer cites examples from studies of the clinical outcomes for a class of once-promising antipsychotic drugs as well as from more theoretical research.  This is a scary situation given the inferential nature of most scientific research.  Each set of observations represents an opportunity to disconfirm a hypothesis.  As long as subsequent observations don’t lead to disconfirmation, our confidence in the hypothesis grows.  The decline effect suggests that replication is more likely, over time, to disconfirm a hypothesis than not.  Under those circumstances, it’s hard to develop sound theory.

Given that market researchers apply much of the same reasoning as scientists in deciding what’s an effect and what isn’t, the decline effect is a serious threat to creating customer knowledge and making evidence-based marketing decisions. (more…)