 Another aspect of this debate that has received a great deal of consideration concerns the mathematical tools necessary for identifying when a particular level of biological organization meets the criteria for being an  interactor.[4]  Overall, while many of the suggested techniques have had strengths, no one approach to this aspect of the interactor question has been generally accepted and indeed it remains the subject of debate in biological circles (Okasha 2004b,c). Detailed work on two of the major techniques, the Price equation and contextual analysis, has indicated that neither approach is universally applicable, on the grounds that neither provides a proper causal decomposition in all varieties of selection (Okasha 2006). Specifically, it appears that while contextual analysis may be superior in most cases of multi-level selection, the Price equation may be more useful in certain cases of genic selection (Okasha 2006).