Centralization key to this algorithm M Miglis, Back and Neck Care Center, Melbourne, FL 21 August 2007 The algorithm includes determination as to whether or not centralization is occuring at a key point in responose to Question 2 (Reference: Table 1). Skill in determining the presence or absence of centraliztion has been shown to be sensitive to the level of training of the examiner. That is, examiners with formal training in the McKenzie method have been shown to be more reliable in eliciting the centralization phenomenon than untrained counterparts. Given the fact that many examiners have little or no supervised training in this method, how reliable is a pivotal finding of "no centralization"? Isn't this finding especially critical, since it leads along the decision tree to other forms of assessment (segmental provocaton signs, neurodynamic signs, etc.)when, in fact, a false negative for centralization may actually be present? Centralization may take 3-5 assessment sessions to determine. Given the key importance of centralization to this algorithm, wouldn't this suggest the importance of formal training in the McKenzie method, a method notoriously easy to conceptualize but challenging in actual clinical application? With so many other paths to take in this algorithm, shouldn't there be a safeguard against prematurely bypassing centralization in a conscious or unconscious rush to apply whatever other training one is most familiar with? Competing interests The author has no financial interest in the McKenzie method. He is enthusiastic based upon clinical experience and existing scientific literature supporting the centralization phenomenon.