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Not quite right

Posted by RobertPOShea on 20 Sep 2007 at 00:14 GMT

Participants randomized to the control group received an educational booklet, designed by the British Physiotherapy Association that has been previously validated to compare with active physiotherapy[7].
http://plosone.org/article/info:doi/10.1371/journal.pone.0000919#article1.body1.sec2.sec2.sec2.p1

The wording here is ambiguous. One interpretation is that Szczurko et al.'s control condition is equivalent to a full course of physiotherapy. The other (correct) interpretation is that Szczurko et al. used a booklet that had been used in other research.

The study Szczurko et al. cite (Frost et al., 2004) showed that a single visit, lasting up to an hour, to a physiotherapist for advice was just as effective as a standard course of physiotherapy involving a one-hour assessment and up to five 30-minute treatment sessions. Both groups of participants in that study received the same educational booklet. That is, the booklet was a constant, the amount of time spent with a physiotherapist was the manipulated variable.

The first interpretation of Szczurko et al.'s sentence is incorrect because Frost et al. did not show the booklet to be effective by itself.