fa Are clustering effects accounted for in statistical analysis in leading dental specialty journals? ارتودنسی Orthodontics پژوهشي Research <p> <strong>Objectives</strong></p><p>  In dental research multiple site observations within patients or taken at various time intervals are commonplace. These clustered observations are not independent statistical analysis should be amended accordingly. This study aimed to assess whether adjustment for clustering effects during statistical analysis was undertaken in five specialty dental journals. </p><p> <strong>Methods</strong> </p><p> Thirty recent consecutive issues of Orthodontics (OJ), Periodontology (PJ), Endodontology (EJ), Maxillofacial (MJ) and Paediatric Dentristry (PDJ) journals were hand searched. Articles requiring adjustment accounting for clustering effects were identified and statistical techniques used were scrutinized. </p><p> <strong>Results</strong></p><p>  Of 559 studies considered to have inherent clustering effects, adjustment for this was made in the statistical analysis in 223 (39.1%). Studies published in the Periodontology specialty accounted for clustering effects in the statistical analysis more often than articles published in other journals (OJ vs. PJ: OR=0.21, 95% CI: 0.12, 0.37, p<0.001 MJ vs. PJ: OR=0.02, 95% CI: 0.00, 0.07, p<0.001 PDJ vs. PJ: OR=0.14, 95% CI: 0.07, 0.28, p<0.001 EJ vs. PJ: OR=0.11, 95% CI: 0.06, 0.22, p<0.001). A positive correlation was found between increasing prevalence of clustering effects in individual specialty journals and correct statistical handling of clustering (r=0.89). </p><p> <strong>Conclusions</strong></p><p>  The majority of studies in 5 dental specialty journals (60.9%) examined failed to account for clustering effects in statistical analysis where indicated, raising the possibility of inappropriate decreases in p-values and the risk of inappropriate inferences. </p><hr><p></p><p> <strong>Source: </strong>Journal of Dentistry</p><p> <a href="http://www.jodjournal.com/article/S0300-5712(12)00314-4/abstract" target="_blank"><font color="#0000ff">Full Text</font></a></p> Clustering, Statistics, Dental 0 0 http://idai.ir/browse.php?a_code=A-10-32-2122&slc_lang=fa&sid=1 Padhraig S.Fleming 10031947532846009947 10031947532846009947 Yes Barts and The London School of Medicine and Dentistry, Institute of Dentistry, Queen Mary University of London, United Kingdom Despina Koletsi 10031947532846009948 10031947532846009948 No Department of Orthodontics, School of Dentistry, University of Athens, Greece Agry Polychronopoulou 10031947532846009949 10031947532846009949 No Department of Community and Preventive Dentistry, School of Dentistry, University of Athens, Athens, Greece Theodore Eliades 10031947532846009950 10031947532846009950 No Department of Orthodontics and Paediatric Dentistry, Center for Dental Medicine, Faculty of Medicine, University of Zurich, Switzerland Nikolaos Pandis 10031947532846009951 10031947532846009951 No Department of Orthodontics and Dentofacial Orthopedics, Dental School/Medical Faculty, University of Bern, Switzerland