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Open Access Study protocol

Platelet-rich plasma (PRP): an adjuvant to hasten hamstring muscle recovery. A randomized controlled trial protocol (ISCRTN66528592)

Mohamad Shariff A Hamid*, Mohamed Razif Mohamed Ali, Ashril Yusof and John George

  • * Corresponding author: Mohamad S A Hamid ayip@um.edu.my

  • † Equal contributors

BMC Musculoskeletal Disorders 2012, 13:138  doi:10.1186/1471-2474-13-138

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Sample size calculation faulty?

Reinhard Vonthein   (2014-10-17 12:20)  Universitat zu Lubeck email

Inserting the numbers given into the formula provided gives an alternative mean time to return to play close to zero. What is the rationale for that assumption?

Quoted RTP times are obviously from a positively skewed distribution and may be censored at 16 weeks. Together with the small sample sizes these facts speak against planing a t-test as implied by the formula.

 

Competing interests

None declared

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